GRADE 12 NOTES - PHYSICAL SCIENCE PAPER 2: CHEMISTRY STUDY GUIDES

GRADE 12 NOTES – PHYSICAL SCIENCE PAPER 2: CHEMISTRY STUDY GUIDES Are you Preparing for your Grade 12 Physical Science Paper 2 exam? Are you feeling overwhelmed by the vastness of the chemistry syllabus? Fear not! In this article, we’ve compiled a comprehensive set of study guides to help you master the intricacies of chemistry and tackle your exam with confidence.

Colour Diagrams: Acid-base Indicators*

color diagrams kghjs

Overview

Dear Grade 12 learner

This Mind the Gap study guide helps you to prepare for the end-of-year CAPS Grade 12 exam.
The study guide does NOT cover the entire curriculum, but it does focus on core content of each knowledge area and points out where you can earn easy marks.

You must work your way through this study guide to improve your understanding, identify your areas of weakness and correct your own mistakes.

To ensure a good pass, you should also cover the remaining sections of the curriculum using other textbooks and your class notes.

Overview of the Grade 12 exam
The following topics make up each of the TWO exam papers that you write at the end of the year:

Cognitive level	Description	Paper 2 (Chemistry)
1	Remembering/Recall	15%
2	Understanding/Comprehension	40%
3	Applying and analysing	35%
4	Evaluating and creating (synthesis)	10%

Paper

Type of questions

Duration

Total

Date

Marking

Chemistry

10 multiple-choice questions – 20 marks
Structured questions – 130 marks

3 hours

150

October/November

External

Paper 2: Chemistry Focus
Content	Marks	Total	Duration	Weighting of cognitive levels
Chemical change	84	150 marks	3 hours	15	40	35	10

How to use this study guide

This study guide covers selected parts of the different topics of the CAPS Grade 12 curriculum in the order they are usually taught during the year. The selected parts of each topic are presented in the following way:

An explanation of terms and concepts;
Worked examples to explain and demonstrate;
Activities with questions for you to answer; and
Answers for you to use to check your own work.

The activities are based on exam-type questions. Cover the answers provided and do each activity on your own. Then check your answers. Reward yourself for things you get right. If you get any incorrect answers, make sure you understand where you went wrong before moving on to the next section. In these introduction pages, we will go through the mathematics that you need to know, in particular, algebra and graphs. These are crucial skills that you will need for any subject that makes use of mathematics. Make sure you understand these pages before you go any further.

Top 10 study tips

Have all your materials ready before you begin studying – pencils, pens, highlighters, paper, etc.
Be positive. Make sure your brain holds on to the information you are learning by reminding yourself how important it is to remember the work and get the marks.
Take a walk outside. A change of scenery will stimulate your learning. You’ll be surprised at how much more you take in after being outside in the fresh air.
Break up your learning sections into manageable parts. Trying to learn too much at one time will only result in a tired, unfocused and anxious brain.
Keep your study sessions short but effective and reward yourself with short, constructive breaks.
Teach your concepts to anyone who will listen. It might feel strange at first, but it is definitely worth reading your revision notes aloud.
Your brain learns well with colours and pictures. Try to use them whenever you can.
Be confident with the learning areas you know well and focus your brain energy on the sections that you find more difficult to take in.
Repetition is the key to retaining information you have to learn. Keep going – don’t give up!
Sleeping at least 8 hours every night, eating properly and drinking plenty of water are all important things you need to do for your brain. Studying for exams is like strenuous exercise, so you must be physically prepared.

Mnemonics

A mnemonic code is a useful technique for learning information that is difficult to remember. Here’s the most useful mnemonic for Mathematics, Mathematical Literacy, and Physical Science:
BODMAS:

B– Brackets
O– Of or Orders: powers, roots, etc.
D– Division
M– Multiplication
A– Addition
S– Subtraction

Throughout the book you will be given other mnemonics to help you remember information. The more creative you are and the more you link your ‘codes’ to familiar things, the more helpful your mnemonics will be.

Mind maps

There are several mind maps included in the Mind the Gaps guides, summarising some of the sections.
mind maps ajhbjh
Mind maps work because they show information that we have to learn in the same way that our brains ‘see’ information. As you study the mind maps in the guide, add pictures to each of the branches to help you remember the content. You can make your own mind maps as you finish each section.
How to make your own mind maps:

Turn your paper sideways so your brain has space to spread out in all directions.
Decide on a name for your mind map that summarises the information you are going to put on it.
Write the name in the middle and draw a circle, bubble or picture around it.
Write only key words on your branches, not whole sentences.
Keep it short and simple.
Each branch should show a different idea.
Use a different colour for each idea.
Connect the information that belongs together.
This will help build your understanding of the learning areas.
Have fun adding pictures wherever you can. It does not matter if you can’t draw well.

On the day of the exam

Make sure you have all the necessary stationery for your exam, i.e. pens, pencils, eraser, protractor, compass, calculator (with new batteries). Make sure you bring your ID document and examination admission letter.
Arrive on time, at least one hour before the start of the exam.
Go to the toilet before entering the exam room. You don’t want to waste valuable time going to the toilet during the exam.
Use the 10 minutes reading time to read the instructions carefully. This helps to ‘open’ the information in your brain. Start with the question you think is the easiest to get the flow going.
Break the questions down to make sure you understand what is being asked. If you don’t answer the question properly you won’t get any marks for it. Look for the key words in the question to know how to answer it. Lists of difficult words (vocabulary) is given a bit later on in this introduction.
Try all the questions. Each question has some easy marks in it so make sure that you do all the questions in the exam.
Never panic, even if the question seems difficult at first. It will be linked with something you have covered. Find the connection.
Manage your time properly. Don’t waste time on questions you are unsure of. Move on and come back if time allows. Do the questions that you know the answers for, first.
Write big and bold and clearly. You will get more marks if the marker can read your answer clearly.
Check weighting – how many marks have been allocated for your answer? Take note of the ticks in this study guide as examples of marks allocated. Do not give more or less information than is required.

Question words to help you answer questions

It is important to look for the question words (the words that tell you what to do) to correctly understand what the examiner is asking. Use the words in the table below as a guide when answering questions.

Question word	What is required of you

Analyse	Separate, examine and interpret

Calculate	This means a numerical answer is required – in general, you should show your working, especially where two or more steps are involved

Classify	Group things based on common characteristics

Compare	Point out or show both similarities and differences between things, concepts or phenomena

Define	Give a clear meaning

Describe	State in words (using diagrams where appropriate) the main points of a structure/process/phenomenon/ investigation

Determine	To calculate something, or to discover the answer by examining evidence

Differentiate	Use differences to qualify categories

Discuss	Consider all information and reach a conclusion

Explain	Make clear; interpret and spell out

Identify	Name the essential characteristics PAY SPECIAL ATTENTION

Label	Identify on a diagram or drawing

List	Write a list of items, with no additional detail

Mention	Refer to relevant points

Name	Give the name (proper noun) of something

State	Write down information without discussion

Suggest	Offer an explanation or a solution

Tabulate	Draw a table and indicate the answers as direct pairs

Vocabulary

The following vocabulary consists of all the difficult words used in Mind the Gap Mathematics, Mathematical Literacy, and Physical Science. We suggest that you read over the list below a few times and make sure that you understand each term. Tick next to each term once you understand it so you can see easily where the gaps are in your knowledge.

(adj)	adjective: describing word such as “big”
(adv)	adverb: describing word for verbs, such as “fast”
(prep)	preposition: a word describing a position, such as “on”, “at”
(sing)	singular: one of
(pl)	plural: more than one of
(abbr)	abbreviation
General terms
Term	Meaning
A

abbreviate	(v). Make shorter.
abundant	(adj). Having plenty of something.
accept	(v). Agree to receive something; say yes to; believe; tolerate something.
account for	(v). Explain why.
adjacent	(adj). Next to something.
affect	(v). Make a difference to; touch the feelings of. Do not confuse with effect. See effect.
analyse	(v). Examine something in detail.
ante-	(prep). Before (e.g., ante-natal – before birth)
anti-	(prep). Against (e.g., anti- apartheid – against apartheid).
apparent	(adj). Clearly visible; the way something seems to be or the way it appears.
appear	(v). Come into sight; seem to be.

approximate	(v. & adj.). Come close to (v); roughly, almost, not perfectly accurate, close but not exact. The verb is pronounced “approxi-mayt” and the adjective is pronounced “approxi-mitt”.
aquatic	(adj). Growing or living near or in water.
arbitrary	(adj). Based on random choice; unrestrained and autocratic.
C

category	(n). Class or group of things.
cause	(v). Make something happen.
cause	(n). The person or thing that makes something happen; an aim or movement to which a person is committed.
causality	(n). Someone or something responsible for a result.
collide	(v). To crash into; to hit.
complex	(adj). Consisting of many different parts; not easy to understand (n) a group or system of things connected in a complicated way.
component	(n). A part.
compose	(v). To make up from parts.
composite	(n). Something made up of parts; (adj) made up of several parts.
condition	(n). The state something is in; the situation that must exist before something else is possible.
conjunction	(n). When two or more things come together at the same point; in grammar, a part of speech that connects words, sentences, phrases or clauses, e.g.: “and”
consider	(v). Think about.
contrast	(v). Show the difference between;
	(n). something that is very different from what it is being compared with.
conversely	(adv). The opposite of.
counteract	(v). Act against something in order to stop it.
D

data (pl), datum (sing)	(n). Information given or found.
deduce	(v). To work something out by reasoning.

deduction	(n). Conclusion or idea that someone has worked out.
define	(v). Give the meaning of a word or words.
definition	(n). The meaning of a word or words.
deliver	(v). To bring and hand over.
denote	(v). To refer to or mean something.
determine	(v). Work out, usually by experiment or calculation.
discreet	(adj). Careful, polite.
discrete	(adj). Single, separate, distinct, a part.
E
effect	(n). Result.
effect	(v). Carry out, do, enact.
eject	(v). Force or throw something or someone out violently or suddenly.
elapse	(v). Pass by or finish, e.g., time.
establish	(v). Show or prove, set up or create.
exceed	(v). Go beyond.
excess	(n). More than necessary.
excluding	(prep). Not including.
exclusive	(adj). Excluding or not admitting other things; reserved for one particular group or person.
exemplar	(n). A good or typical example.
exempt	(v). To free from a duty.
exempt	(adj). Be freed from a duty.
exemption	(n). Being freed from an obligation.
exhibit	(v). To show or display.
exhibit	(n). A part of an exhibition.
expel	(v). Force someone or something to leave a place. Eject.
extent	(n). The area covered by something.
F
factor	(n). A circumstance, fact or influence that contributes to a result; a component or part.
factory	(n). A place where goods are made or put together from parts.

find	(v). Discover or locate.
find	(n). Results of a search or discovery.
finding	(n). Information discovered as the result of an inquiry.
fixed	(adj). Not able to move, attached; or repaired, not broken.
format	(n). Layout or pattern; the way something is laid out.
G
global	(adj). Found all over the world (globe).
H
hazard	(n). Something dangerous.
heterogeneous	(adj). Made up of many different parts.
homogeneous	(adj). Uniform, made up of the same types of parts.
hypothesis	(n). A theory or proposed explanation.
hypothetical	(adj). Theoretical or tentative; waiting for further evidence.
I
identify	(v). Recognise or point out.
illustrate	(v). Give an example to show what is meant; draw.
impair	(v). Weaken or damage.
imply	(v). Suggest without directly saying what is meant.
indicate	(v). Point out or show.
initial	(n). First.
initiation	(n). The action of beginning something; the action of admitting somebody into a group or organisation.
insufficient	(adj). Not enough.
interchange-	(adj). Can be swapped or
able	exchanged for each other.
investigate	(v). Carry out research or a study.
issues	(v). Comes out of.
issues	(n). An important problem or a topic for debate.

M
macroscopic	(adj). Visible without being made bigger.
manipulate	(v). Handle or control (a thing or a person).
microscopic	(adj). Very small, not visible without being made bigger.
motivate	(v). Give someone a reason for doing something.
multiple	(adj). Many.
N
negligible	(adj). Small and insignificant; can be ignored. From “neglect” (ignore).
numerical	(adj). Relating to or expressed as a number or numbers.
numerous	(adj). Many.
O
observe	(v). Look at; watch carefully.
obtain	(v). Get.
occur	(v). Happen.
operate	(v). Work; drive; control.
optimal	(adj). Best; most favourable.
optimum	(adj). Best; (n) the most
	favourable situation for growth or success.
overabundance	(n). More than enough; too much.
P
phenomenon	(n). A fact or situation that is seen to exist or happen.
phenomena	(n). Plural of phenomenon.
prefix	(n). Part of a word that is attached to the beginning of many different words, changing their meaning, e.g., prehistoric – before written records were kept.
prepare	(v). Make ready before an event; set things up.
principal	(n). Head of a school.
principal	(adj). Main or most important.
principle	(n). A basic truth that guides the way a person behaves.
provide	(v). Make available for use; supply.

Q
quality	(n). The standard of something compared to other similar things; a characteristic of someone or something.
R
reciprocal	(adj). Given or done in return.
record	(v). Make a note of something in order to refer to it later (pronounced ree-cord).
record	(n). A note made in order to refer to it later; evidence of something; a copy of something (pronounced rec-cord.
relative	(adj). Considered in relation to something else; compared to.
relative	(n). A family member.
represent	(v). Be appointed to act or speak for someone; amount to.
resolve	(v). Finalise something or make it clear; bring something to a conclusion.
respect	(v). Admire something or someone; consider the needs or feelings of another person.
respectively	(adj). In regards to each other, in relation to items listed in the same order.
S
simultaneously	(adv). At the same time.
site	(n). Place.
suffice	(v). Be enough.
surplus	(adj). More than is needed.
survey	(n). A general view, examination, or description of someone or something.
survey	(v). Look closely at or examine; consider a wide range of opinions or options.
T
tendency	(n). An inclination to do something in a particular way; a habit.
tertiary	(adj). Third level.

U
uniform	(n). Standardised clothing.
uniform	(adj). Remaining all the same at all times; unchanging.
V
verify	(v). Show to be true; check for truth; confirm.
vice versa	(adv). The other way round.
versus	(prep). Against. Abbreviated “vs” and sometimes “v”.

Technical terms

A
absorption	(n). To take into; the process of
	taking something in.
account	(n. & v.). Finance: A record of
	income and expenditure. To
	explain (v), e.g. “Account for why
	the sky is blue”.
acetic	(adj). Pertaining to vinegar; an
	organic molecule containing two
	carbons. See organic, eth- for
	more.
acetone	(n). Propanone. CH₃COCH₃; the
	ketone of acetic acid. See ketone
	for more.
acetylene	(n). Ethyne, C₂H₂. Used in welding
	torches (blowtorches). See also
	alkene.
acid	(n). A proton donor or substance
	that ionises into H+ or H₃O+ when
	dissolved in water; sour-tasting
	substance; corrosive; pH below 7.
	See also base and alkali.
acidified	(adj). To have been made acidic.
acidity	(n). How acid something is.
activated	(adj). Made to function. Chemistry:
	something moved into an unstable
	higher-energy level or state.
	Usually “activated complex”, the
	combination of reactants just
	before they turn into products. See
	also reactant, reagent, product.
activation	(n). The process of activating
	something. “Activation energy”,
	the required energy to create an
	activated complex.
aerosol	(n). A solution of substances in air or
	other gas, e.g. as in an aerosol can.

affinity	(n). A liking for something;
	an attraction to something; a
	tendency to react with something
	(chemistry). See also paraffin.
alcohol	(n). In common usage, ethanol
	C₂H₅OH. Technically, any organic
	substance or molecule containing
	an -OH group. See organic.
aldehyde	(n). Any organic molecule containing
	-CHO, formed by oxidising alcohols.
	See alcohol and organic.
algae	(n). Adjective: algal (pertaining to
	algae); an aquatic plant (lives in
	water), which lacks leaves, stems,
	roots.
algebra	(n). A mathematical system
	where unknown quantities are
	represented by letters, which
	can be used to perform complex
	calculations through certain rules.
alkali	(n). See base.
alkane	(n). An organic molecule or
	compound or substance which
	contains only single bonds
	between carbons. See organic.
alkene	(n). An unsaturated organic
	molecule, compound or substance,
	which contains at least one double
	bond between carbons. See
	organic and unsaturated.
alkyl	(n). A prefix (word part) which shows
	that the word after it has an alkane
	group attached to it, by removing
	one hydrogen from the alkane.
alkyne	(n). An unsaturated organic
	molecule, compound or substance,
	which contains at least one triple
	bond between carbons. See
	organic and unsaturated.
amalgam	(n). General use: a mixture. In
	chemistry, specifically a mercury
	alloy.
amide	(n). An organic compound
	containing the group -C(O)NH₂; an
	inorganic compound containing
	the group NH₂^–.
amine	(n). The same as an amide except
	the -NH₂ can be attached to
	anything, and does not have the
	CO group shown above.
ammonia	(n). NH₃.
ammonium	(adj). NH₄+, found as a cation or as
	part of a salt. See salt and cation.
amphiprotic	(n). See ampholyte.
ampholyte	(n). A substance that can act as an
	acid or base. See acid, base.

anions	(n). A negative ion. See cation, ion.
anode	(n). The negative electrode of
	a cell or current supplier; the
	positive electrode of an electrolytic
	system; attracts negative ions. See
	electrode, cathode.
antacid	(n). A substance used to neutralise
	(react with) acid. E.g. chalk. See
	acid, neutralise.
apparatus	(n). Equipment; parts of a scientific experiment.

aqueous	(n). Dissolved in water.
Arrhenius	(n). Arrhenius’ theory of acids and bases: That acids produce H+ or H₃O+ in water, and bases produce OH–. See Brønsted-Lowry.
asbestos	(n). A fireproof fibrous substance containing silicon used for fireproofing.
asbestosis	(n). A lung disease caused by inhaling asbestos fibres, can lead to cancer.
atm	(n). Abbreviation: atmospheres of pressure (1 atm = 101,3 kPa). The pressure of the air at sea level. Same as “bar” (barometric pressure).
ATM	(n). Abbreviation: automatic teller machine.
atmosphere	(n). The air or the gases surrounding a planet; the sky; as a unit of measurement, see atm.
atmospheric	(adj). To do with the atmosphere.
atom	(n). The smallest unit of a chemical element, which, if broken down further, no longer behaves in the same way chemically. Consists of a nucleus or centre part which is positively charged, and an electron cloud (negatively charged) which surrounds the nucleus. See nuclear.
attract	(v). To bring something closer.
average	(n). Mathematics: The sum of parts divided by the quantity of parts. In common use: neither very good, strong, etc., but also neither very weak, bad, etc; the middle. In Physical Science and Mathematics: if you are asked to find the average, you always have to calculate it using the information you have. For example, the average of (1;2;3) is 2, because (1+2+3)/3 = 2. See also mean, median and mode.
avogadro (constant or number)	(n). 6,023 × 1023 particles; one mole. See mole and mol.
axis (sing), axes (pl, pronounced “akseez”)	(n). A line along which points can be plotted (placed), showing how far they are from a central point, called the origin. See origin. “Vertical axis” or “y-axis” refers to how high up a point is above the origin (or how far below). “Horizontal axis” or “x-axis” refers to how far left or right a point is away from the origin.

B


bakelite	(n). A type of hard, brittle plastic
	that can’t melt once it has set
	or taken shape (thermosetting),
	made from phenol C₆H₅OH, and
	formaldehyde (methanal), CH₂O.
balance	(v. & n.). To make two things equal
	(v); a scale to weigh objects (n).
	Chemistry: to compare two sides
	of a chemical equation and make
	sure that there are the same
	numbers of atoms on both sides.
base	(n). A proton acceptor, or substance
	that ionises into OH– when
	dissolved in water; a bitter-tasting
	substance, corrosive, pH above 7.
	See also acid. Do not confuse with
	common everyday use, meaning
	“the bottom” or “low”.
basic	(n). Bitter or made of a base. Do not
	confuse with popular use, meaning
	“low” or “simple” or “crude”.
battery	(n). A collection of cells connected
	in series (end-to-end). See cell. In
	common use, “battery” is used to
	mean the same as “cell” (e.g. a
	penlight or AA cell), but this use is
	incorrect except for a car battery,
	which consists of a series of cells.
benzoic	(adj). Contains benzene or a
	benzene ring.
bi-	(prefix). Two.
bicarbonate	(n). Any salt containing the ion
	-HCO –. So called because the
	3
	carbonate (CO₃2–) attaches to
	another ion and the hydrogen
	(two bonds). The name “hydrogen
	carbonate” is now preferred.
biodegradable	(adj). Can be broken down by
	natural processes e.g. involving
	bacteria, moulds, fungus, etc.
biodiesel	(n). Diesel (a type of petrol) made
	from plants rather than fossil fuels
	(coal, oil).

BODMAS	(abbr). Brackets, of/orders
	(powers, squares, etc), division,
	multiplication, addition, subtraction.
	A mnemonic (reminder) of the
	correct order in which to do
	mathematical operations.
boil	(v). Physics: to cause a liquid’s
	vapour pressure to exceed
	the pressure of the gas in the
	container, usually by heating it,
	but it can be done by lowering
	the pressure of the gas in the
	container, too. See vapour
	pressure. In common usage, to
	make a liquid hot until it bubbles.
bond	(n). A connection. In physics and
	chemistry, between atoms and
	molecules.
breadth	(n). How wide something is. From
	the word “broad”.
brine	(n). A saturated salt solution (a
	mixture of water and salt which
	can’t dissolve any more salt).
bromide	(n). Something containing bromine,
	usually one ion. See ion.
bromo-	(prefix). Something containing
	bromine.
bromothymol	(n). A type of acid-base indicator
(blue)	used to tell whether something
	is an acid or base. Turns blue (in
	base) or yellow (in acid).
Brønsted-Lowry	(n). A theory of acids and bases
	which says that acids are proton
	donors (they give away protons),
	and bases are proton acceptors
	(they take protons). Since H+ is
	just a proton, this does not mean
	something different from the
	Arrhenius theory that an acid is a
	substance that dissolves into H+ in
	water. See proton, Arrhenius.
but-	(prefix). Four carbons. Pronounced
	“beaut”. E.g. butane is a four-
	carbon alkane.

C

calibrate	(v). To adjust a measuring tool
	or measurement against a
	known accurate measurement to
	ensure that the measuring tool or
	measurement is accurate; to check
	a measurement or measuring
	tool’s accuracy; to mark with
	accurate measurements using a
	standard scale like cm, mm, mℓ,
	etc. Common use: to assess or
	evaluate carefully.

carbohydrate	(n). Organic compounds containing
	carbon and hydrogen, occurring
	in foods and living tissues and
	including sugars, starch, and
	cellulose. They contain hydrogen
	and oxygen in the same ratio
	as water (2:1). Not the same
	as hydrocarbons, which are any
	substances containing mostly
	hydrogen and carbon.
carbonate	(n). -CO₃^2–
carbonic	(adj). Anything containing carbon,
	or more specifically, CO₂
carbonyl	(adj). Containing double bonded
	carbon and oxygen: =C=O.
carboxyl	(adj). Containing -COOH.
carboxylic	(adj). Carboxyl-containing.
Cartesian	(adj). Anything believed or
	proposed by Rene Descartes.
	In particular, the x-and-y axis
	coordinate system.
catalyst	(n). A substance that alters the
	rate of a chemical reaction without
	itself being consumed in the
	reaction. Without qualification, or
	as “positive catalyst”, something
	that starts or speeds up a reaction.
	A “negative” catalyst slows down a
	reaction.
catalytic	(n). Containing or using a catalyst.
cathode	(n). The positive electrode of a cell
	or current supplier; the negative
	electrode of an electrolytic
	system; attracts positive ions. See
	electrode, anode, ion.
cathodic	(adj). Involving a cathode. Cathodic
	protection: To use a more reactive
	metal to protect a less reactive
	metal from oxidation. See anode,
	cathode, oxidise.
cation	(n). A positively charged ion. See
	anion, ion.
caustic	(adj). Basic; a base.
cell	(n). An apparatus that generates
	electricity using electrochemistry.
	An AA or Penlight battery, as it is
	commonly called, is a cell. A car
	battery consists of a number of
	cells inside a single container.
CFC	(n). A chlorofluorocarbon. A
	substance containing carbon,
	chlorine and fluorine. Responsible
	for breaking down ozone (O₃) which
	protects us from too much UV
	radiation from the sun.

chain	(n). Chemistry: a long series of
	atoms bonded together, usually
	carbon.
charge	(n). Chemistry: having too
	many or too few electrons
	(most commonly), resulting in
	a substance ionising. A positive
	charge results from too few
	electrons, and a negative charge
	from too many electrons. Physics:
	a basic feature of all physical
	electromagnetic particles, except,
	e.g. neutrons and photons, which
	have zero charge. All protons have
	a positive charge, all electrons
	have a negative charge.
chart	(v). To draw a diagram comparing
	values on Cartesian axes.
Le Châtelier’s	(n). That in reversible reactions,
Principle	chemical systems will favour the
	forward or reverse reaction to
	minimise the change imposed
	on the system. If a chemical
	equilibrium is disturbed by
	changing the conditions, the
	position of equilibrium moves to
	counteract the change.
chloro-	(prefix). Containing chlorine.
chlorofluoro-	See CFC.
carbons
chloroform	(n). CHCℓ₂. A liquid formerly used
	as an anaesthetic.
chlorophyll	(n). A green substance found
	in plants which enables
	photosynthesis (broadly,
	generating food from CO₂). See
	photosynthesis.
coefficient	(n). A constant value placed
	next to an algebraic symbol as a
	multiplier. Same as constant (see
	below). Or: a multiplier or factor
	that measures a property, e.g.
	coefficient of friction.
combustion	(n). The process of burning, usually
	in oxygen. Rapid oxidation.
completion	(n). Chemistry: when a reaction
	no longer proceeds (continues)
	because it has run out of one
	or more of the reactants. See
	reactant, reaction.
complex	(n). See activated.
(activated)

compound	(n). A substance made up of
	molecules consisting of more
	than one different type of atom,
	chemically bonded in a constant
	ratio. E.g. Water (H₂O) is a
	compound, but Sulphur powder
	(S) is not. In a compound, the
	original chemicals (reactants) have
	reacted or merged to form a new
	substance. Compare to mixture.
compressed	(adj). Subjected to pressure,
	squashed.
concentration	(n). The number of moles of
	substance per unit volume.
	See mol, moles. How “strong” a
	solution is. See solution.
condensation	(n). When a vapour or gas cools
	down and starts to collect into
	larger droplets; changing phase
	from vapour or gas to liquid.
	Condensation reaction: to produce
	a larger molecule from two smaller
	ones.
conditions	(n). Physics and Chemistry: how
(STP)	the environment is: temperature
	and pressure. STP (Standard
	Temperature and Pressure is 25°C
	and 1 atm).
conjugate	(n). To join together. Chemistry: two
	things that belong together, e.g.
	conjugate acid-base pairs.
conservation	(n). A law which describes
	something that does not change.
	E.g. the conservation of matter-
	energy says that matter-energy
	cannot be created or destroyed,
	only transformed from one form
	into another. There are a number
	of other conservations, e.g.
	momentum and torque.
constant	(n). See coefficient. Means
	“unchanging”.
contaminate	(v). Chemistry: to introduce
	impurities or other substances
	which are not meant to be part of
	a reaction.
control	(n. and v.). To ensure something
	does not change without
	being allowed to do so (v);
	an experimental situation to
	which nothing is done, in order
	to compare to a separate
	experimental situation, called the
	‘experiment’, in which a change
	is attempted. The control is then
	compared to the experiment to see
	if a change happened.

control variable	(n). A variable that is held constant
	in order to discover the relationship
	between two other variables.
	“Control variable” must not be
	confused with “controlled variable”
	(see independent variable).
coordinate	(n). The x or y location of a point on
	a Cartesian graph, given as an x or
	y value. Coordinates (pl) are given
	as an ordered pair (x, y).
correlate	(v). To see or observe a
	relationship between two things,
	without showing that one causes
	the other.
correlation	(n). That there is a relationship
	between two things, without
	showing that one causes the other.
correspond	(v). To pair things off in a
	correlational relationship. For two
	things to agree or match. E.g. A
	corresponds to 1, B corresponds to
	2, C corresponds to 3, etc.
corrode	(v). Chemistry: to destroy by
	gradual chemical action. Usually
	refers to acidic action. Compare
	to erode. General use: to destroy
	gradually.
corroding	(adj). A process or substance
	that corrodes; to be subject to
	corrosion.
corrosion	(n). To corrode.
corrosive	(adj). To be capable of corroding
	something.
counteract	(v). Oppose or resist.
covalent	(adj). Chemistry: a bond which
	results from sharing electrons
	between atoms. Compare ionic
	bond.
cracking	(n). A process of breaking a
	complex organic molecule into
	simpler parts using heat and
	pressure.
cubed	(adj). The power of three;
	multiplied by itself three times.
cubic	(adj). Shaped like a cube; having
	been multiplied by itself three
	times.
current	(n). Flowing electrons.

D

decompose	(v). To break down into
	components.

degradable	(adj). Capable of breaking down or
	being broken down.
dehydrating	(adj). To remove water from. A
(agent)	“dehydrating agent” is a substance
	which can remove water from
	another substance. E.g. H₂SO₄,
	ethanol.
dehydration	(n). The process of removing water
	from a substance.
dehydrogena-	(n). The process of removing
tion	hydrogen from a substance.
dehydrohalo-	(n). To remove hydrogen and a
genation	halogen from a substance. See
	halogen.
denominator	(n). See divisor. In popular speech:
	a common factor.
depend	(v). To be controlled or determined
	by something; to require something
	to happen or exist first.
dependent	(adj/n). A variable whose value
(variable)	depends on another; the thing
	that comes out of an experiment,
	the effect; the results. See also
	independent variable and control
	variable. The dependent variable
	has values that depend on the
	independent variable, and we plot
	it on the vertical axis.
depleted	(adj). Having been used up; run
	out of.
deposit	(n). Finance: to place money into
	an account. Physical Science: to
	cover a surface of one substance
	with another substance, e.g. metal
	plating on an electrode.
determine(s)	(v). To cause; to ensure that; to set
(causation)	up so that; to find out the cause of.
di-	(prefix). Two.
diamine	(n). A substance containing two
	amine groups. See amine.
diammonium	(n). Having two ammonium (NH₄)
	groups. See ammonium.
diaphragm	(n). A thin sheet of any substance
	covering a gap. Biology: the muscle
	below the lungs which moves to
	cause breathing. Electrochemistry:
	a thin sheet inside a cell which
	separates the electrodes. It is
	porous and allows solutions
	containing ions through, but serves
	to separate gas products.
difference	(n). Mathematics: subtraction.
	Informally: a dissimilarity. How
	things are not the same.

dilute	(adj. & v). To lower the
	concentration of a solution. See
	solution and concentration (v):
	a solution which has had its
	concentration lowered (adj).
dilution	(n). The opposite of concentration;
	how low a concentration is,
	measured in mol/dm3; the process
	of diluting.
dimer	(n). A molecule made of two
	identical parts. See also polymer.
diode	(n). A semiconductor device with
	two terminals (electrodes), usually
	allowing current to flow in one
	direction only.
diol	(n). A molecule with two alcohol/
	hydroxyl (OH) groups.
dipole	(n). A polarised molecule with a
	distinctly positive and distinctly
	negatively-charged end.
diprotic	(n). Having two protons.
displace	(v). To move or relocate something.
dissipate	(v). To disperse or scatter (e.g.
	gas). Thermodynamics (Energy):
	to cause energy to be lost as heat.
	Popular use: to disappear.
dissociate	(v). To break apart; to no longer be
	associated with.
dissolve	(v). To break up into ions within a
	solution (usually water); to mix a
	solid (usually powder) into a liquid,
	to form a solution. See solution,
	ion. Alternative popular use: to
	bring to an end.
distil(l)	(v). To purify through repeated
	heating of a liquid and collection
	of condensation. The heating
	process causes the liquid to form
	gas or vapour, which condenses
	on the side of the heating vessel
	(container) or an exit tube, leaving
	impurities behind in the heating
	vessel.
distribution	(n). How something is spread
	out. Mathematics: the range and
	variety of numbers as shown on a
	graph.
disturb	(v). Chemistry: to mix or stir a liquid
	or solution; to shake it up.
divisor	(n). The number below the line
	in a fraction; the number that is
	dividing the other number above
	the fraction line. See numerator,
	denominator.

domain	(n). The possible range of x-values
	for a graph of a function. See
	range.
durable	(adj). Tough; something that can
	endure.
dynamic	(adj). Changing often. Relating
	to forces that produce motion.
	Opposite of static. See static and
	electrostatic.

E

ecosystem	(n). An integrated, complex,
	interacting, mutually dependent
	living system or environment.
electric	(adj). Containing electricity
	(electrons).
electro-	(adj). Where chemical reactions
chemical	cause the release of electrons,
	usually into a circuit. General use:
	anything relating to electrical and
	chemical phenomena.
electrode	(n). General use: the point where
	electrons enter or exit a power
	source or a circuit. Specifically
	(Electrochemistry): Part of a circuit
	dipped into a solution to receive or
	release electrons. See anode and
	cathode.
electrolysis	(n). The splitting of a chemical
	into ions. (The chemical is usually
	dissolved in water or another
	solution.) It is done by means of
	electricity. See electrochemical.
electrolyte	(n). A substance (usually liquid
	or gel solution) which contains
	a compound that will be split by
	electricity. Ionisable solutions or
	components.
electromotive	(adj). Usually electromotive force
	or emf. The potential difference
	caused by electromagnetism,
	which causes current to flow.
	Producing a current with
	electromagnetism. See emf.
electron	(n). A fundamental physical
	particle bearing a negative charge,
	weighing approximately 9 × 10−28g,
	which is found around atomic
	nuclei in areas called ‘orbitals’.
	Responsible for electricity and
	chemical reactions. Symbol e–. See
	proton, nucleus.

electroplate	(v). To cover a surface of a less
	valuable substance with a more
	valuable metal, using electrolysis.
element	(n). Mathematics: part of a set
	of numbers. Physics: a pure
	substance made only of atoms of
	one type, with the same number
	of protons in each nucleus. An
	element cannot be broken down
	further without losing its chemical
	properties. Each element has a
	unique atomic number which is the
	number of protons in the nucleus.
	See nucleus, atom, isotope.
	Popular use: part of.
eliminate	(v). To remove or get rid of.
	Mathematics: to cancel a factor
	out of one side of an equation by
	dividing by that factor throughout,
	or by substituting in another
	formula or value that is equal.
	Chemistry: to produce a smaller
	substance as a by-product
	from reacting more complex
	substances, usually water or CO₂;
	in the sense of: to remove those
	molecules from the reaction.
emf	(abbr). Same as electromotive
	force. Always written in lowercase
	(small letters).
emission	(n). Something released, e.g. gas,
	light, heat.
emit	(v). To release.
empirical	(adj). Relating to the senses or to
	things that you can see, touch,
	taste, etc. Chemistry: empirical
	formula: a formula giving the
	proportions of the elements
	present in a compound but not the
	actual numbers or arrangement
	of atoms; the lowest ratio of
	elements without giving structure
	or quantities.
emulsion	(n). Small particles or droplets of
	a substance or liquid which do
	not dissolve in a different liquid;
	suspended or floating within that
	liquid, e.g. to mix oil and water by
	shaking them up.
endothermic	(adj). Taking in heat, ΔH > 0. See
	enthalpy, exothermic.
energetic	(adj). Having a lot of energy;
	performing a lot of work.

energy	(n). Work or the ability to do
	work. There are various forms of
	energy: motion (E_k), light energy
	(photons), electrical energy, heat,
	etc. Energy can neither be created
	nor destroyed, but only converted
	from one form to another. See
	conservation.
enthalpy	(n). The total heat content of a
	system, H, including the chemical
	energy.
equilibria (pl),	(n). The state of being in balance.
equilibrium	Chemistry: when the forward
(sing)	reaction rate is equal to the
	reverse reaction rate. See Le
	Châtelier’s Principle.
erode	(v). To wear away by means of
	friction (rubbing).
ester	(n). An organic compound
	produced by bonding an alcohol
	to a carboxylic (organic) acid,
	by means of dehydration. See
	carboxylic, organic, alcohol,
	dehydration. Responsible for fruit
	flavours and many pleasant odours
	(smells).
esterfication	(n). The production of esters.
estimate	(n., v.). To give an approximate
	value close to an actual value; an
	imprecise calculation.
eth-	(prefix). Containing two carbons.
eutrophication	(n). Excess nutrients in water
	causing excessive plant growth and
	strangulation of a waterway.
evaporate	(v). To change phase of matter
	from liquid to gas. Compare
	sublimate and boil.
excited	(n). The state of being in a higher
	energy level (higher than ground
	state).
exo-	(prefix). Outside of.
exothermic	(adj). Giving off heat, ΔH < 0. See
	enthalpy, endothermic.
exponent	(n). When a number is raised to a
	power, i.e. multiplied by itself as
	many times as shown in the power
	(the small number up above the
	base number). So, 23 means
	2 × 2 × 2. See also cubed.
exponential	(adj). To multiply something many
	times; a curve representing an
	exponent.

extrapolation	(n). To extend the line of a graph
	further, into values not empirically
	documented, to project a future
	event or result. In plain language:
	to say what is going to happen
	based on past results which were
	obtained (gotten) by experiment
	and measurement. If you have
	a graph and have documented
	certain results (e.g. change vs
	time), and you draw the line further
	in the same curve, to say what
	future results you will get, that is
	called ‘extrapolation’. See predict.
extrude,	(v., n.). To push something through
extrusion	a mould or shape, usually a liquid
	or gel through a hole, to create a
	new shape.

F

fahrenheit	(n). A temperature scale based
	on human body temperature.
	Water freezes at 32°F and boils
	at 212°F under standard
	conditions. The conversion
	formula to centigrade/celcius is:
	(˚F – 32) × 5/	9	= ˚C


favoured	(adj). Preferred. Chemistry: in a
	chemical reaction, the direction of
	the reaction after the equilibrium
	is broken.
fermentation	(n). The conversion of a sugar or
	carbohydrate to an alcohol, usually
	by yeast or bacteria.
fertilisation	(n). The process of adding
	nutrients to soil. Biology: the fusion
	of male and female gametes (sex
	cells) into a zygote (group of cells
	that will become a foetus or other
	living organism).
fertiliser	(n). A substance added to soil for
	nutritional reasons.
fixation	(n). The process of fixing on
	something or someone.
fixed	(n). The process of attaching one
(chemistry)	chemical or compound to another.
	E.g. nitrogen fixing is the bonding
	of free N₂ to organic chemicals.
fluid	(n). Any substance that can flow
	and take the shape of a container;
	liquid, some gels, and gas.
fluorescent	(n). Bright, colourful, due to
	changes in energy levels of
	electrons, as seen in fluorescent
	tubes, ink, etc. See reflective.

formic	(prefix). Same as meth-. Contains
	one carbon. From Latin “formica”:
	ant, referring to formic acid, which
	is found in an ant’s sting.
fraction	(n). Mathematics: Not a whole
	number; a representation of a
	division. A part. E.g. the third
	fraction of two is 0,666 or ⅔.
	meaning two divided into three
	parts. Chemistry: a part of a
	solution or mixture separated out
	by distillation. See distil.
function	(n). Mathematics: when two
	attributes or quantities correlate.
	If y changes as x changes, then
	y = f(x). See correlate, graph,
	Cartesian, axis, coordinate. Also:
	a relation with more than one
	variable (mathematics). Chemistry:
	functional group: part of a
	molecule that gives the substance
	its chemical properties in common
	with other similar chemicals.

G

galvanic	(adj). Relating to currents caused
	by a chemical reaction. See
	electrochemistry.
galvanising	(n). To electroplate so as to protect,
	e.g. cover iron with zinc to prevent
	rust.
gas	(n). The third phase of matter.
	When a solid is heated it turns into
	liquid, and when a liquid is heated
	it turns into gas.
gaseous	(adj). In a gas form.
gradient	(n). A slope. An increase or
	decrease in a property or
	measurement. Also the rate of such
	a change. In the formula for a line
	graph, y = mx + c, m is the gradient.
gradually	(adv). To change or move slowly.
graph	(n). A diagram representing
	experimental or mathematical
	values or results. See Cartesian.
graphic	(n., adj.). A diagram or graph
	(n). Popular use: vivid or clear or
	remarkable (adj.).
graphically	(adv). Using a diagram or graph.
	Popular use: to explain very clearly.
groundwater	(n). Water held in the earth
	(underground).
gypsum	(n). Calcium sulphate.

H


Haber (process)	(n). An industrial process to produce
	ammonia from nitrogen and
	hydrogen, using an iron catalyst at
	high temperature and pressure.
haemoglobin	(n). A compound containing
	iron, found in red blood cells,
	responsible for carrying oxygen.
half-cell	(n). One of the sides of an
	electrochemical cell; one of the
	electrodes and the chemical
	solution around it.
half-reaction	(n). The equation for the chemical
	reaction occurring in a half-cell.
halide	(n). A compound containing a single
	halogen, e.g. NaCℓ. See halogen.
halo-	(prefix). Containing a halogen. See
	halogen.
haloalkane	(n). An alkane bonded to a
	halogen. See halogen.
halogen	(n). Any of the elements fluorine
	(F), chlorine (Cℓ), bromine (Br),
	iodine (I), and astatine (At), in
	group VIIA (17) of the periodic
	table. They combine with metals to
	produce salts. See salt.
halogenation	(n). Adding a halogen.
hardness	(n). (Water). Containing salts, usually
	calcium carbonate. If water contains
	too many such salts, soap does
	not function properly and doesn’t
	produce bubbles or foam. “Water’s
	hardness is determined by the
	concentration of multivalent cations
	in the water. Multivalent cations are
	cations (positively charged metal
	complexes) with a charge greater
	than 1+. Usually, the cations have
	the charge of 2+. Common cations
	found in hard water include Ca2+
	and Mg2+.” (Wikipedia).
heat	(n). Physics: a measure of the
	average kinetic energy of the
	molecules or atoms in a substance;
	enthalpy; the energy of an object
	as molecular motion. Alternatively,
	infra-red radiation (heat radiation)
	coming off a body. See body.
homologous	(n). Belonging to the same group
	of things; analogous. Biology:
	a flipper is homologous with a
	leg or arm. Chemistry (organic):
	belonging to the same series of
	molecules, e.g. alkanes: methane,
	ethane, propane; having the same
	functional group.

hydrate	(n). To add water to.
hydration	(n). Having had water added.
	Some salts are hydrated, meaning
	that they have a number of water
	molecules bonded to them, which
	can be removed by heat. Heating
	a hydrated salt changes its colour
	but not the chemical reactions it
	will undergo. See salt.
hydrocarbon	(n). Any compound consisting
	mainly of hydrogen and carbon.
	Compare carbohydrate.
hydrochloric	(adj). Any chemical containing HCℓ.
hydrohalogen-	(n). Adding a hydrogen and halogen
ation	atom to a molecule.
hydrolysis	(n). Splitting by reacting with
	water. Applies to salts and organic
	chemicals. E.g. A haloalkane plus
	water or a dilute NaOH gives an
	alcohol and either a hydrohalide
	or sodium salt. Dissolving a
	salt in water can be considered
	hydrolysis.
hydronium	(n). H	O+ ion.
	3
hydroxide	(n). OH– ion. This usage applies
	specifically to bases (see acid,
	base). In organic molecules, OH– is
	an alcohol functional group called
	the hydroxyl group. See alcohol,
	hydroxyl, diol.
hydroxyl	(n). See hydroxide.
hydroxylamine	(n). An amine with a hydroxyl
	group.

I

ideal	(adj). Not as seen in real
	life; theoretical. Ideal gas: a
	hypothetical gas whose molecules
	occupy negligible space and
	have no interactions, and which
	consequently obeys the gas laws
	(PV = nRT) exactly.
ignition	(n). The start of a combustion
	reaction. Common use: to start
	a car (which has an internal
	combustion engine). See engine,
	combustion.
illuminate	(v). To explain or light up.
immerse	(v). To cover in liquid.
impair	(v). Prevent; hinder; slow down.
impure	(adj). Containing a variety of
	additional chemicals in smaller
	amounts in addition to the main
	chemical.

incandescent	(adj). Giving off light as a result of
	being heated.
independent	(n). The things that act as input
(variable)	to the experiment, the potential
	causes. Also called the controlled
	variable. The independent variable
	is not changed by other factors, and
	we plot it on the horizontal axis. See
	control, dependent variable.
indicator	(n). Chemistry: a substance used
	to check for pH levels, which
	changes colour according to pH.
	See acid, base, pH.
indigo	(n). The colour between violet and
	blue; purplish-blue.
inert	(adj). Chemistry: a chemical or
	element which does not react or is
	difficult to cause to react, e.g. Ne,
	Xe, He. N₂ is sometimes described
	as inert but it’s not in the group of
	Noble Gases. Common use: lazy,
	unwilling to move.
inflammable	(adj). Same as flammable; easily
	set on fire (combustion).
inhibitor	(n). Something that slows down or
	prevents.
inorganic	(adj). Not containing carbon;
	mineral. Exceptions are C, CO, CO₂,
	which, whilst they contain carbon,
	are not considered organic as they
	can be produced during inorganic
	chemical reactions.
insoluble	(adj). Not able to dissolve.
insufficient	(adj). Not enough.
interact	(v). To affect each other, to be
	directly involved with or act on
	each other.
intermediate	(adj). A state in between.
intermolecular	(adj). Between molecules. See
	molecule, intramolecular.
intramolecular	(adj). Within or inside a molecule.
	See molecule, intermolecular.
inversion	(n). Chemistry: turning something
	upside down.
ion	(n). An atom or molecule or part of
	a molecule which has an electrical
	charge due to gaining or losing one
	or more electrons.
ionic (bond)	(adj.). A bond in which electrons
	have been transferred from one
	side of the molecule to another
	resulting in a cation and anion,
	which then attract. E.g. NaCℓ.
ionisation	(n). The process of ionising. See
	ionise.
ionise	(v). To turn into an ion. See ion.

irreversible	(adj). Cannot be reversed. Said
	of certain chemical reactions,
	in which case it specifically
	means that the reaction does not
	spontaneously reverse (not an
	equilibrium reaction). The reaction
	only proceeds in one direction.
	Example: combustion.
isolate	(v). To separate from. Usual use
	in Physical Science means to
	separate one chemical from
	another. Compare insulate, distil.
isomer	(n). A substance with the same
	empirical formula but a different
	structural formula. See empirical,
	structural.
isotope	(n). An element which has a
	different number of neutrons from
	the usual number of neutrons in the
	element. E.g. 12C has 6 protons and
	6 neutrons, but 14C has 8 neutrons
	and 6 protons, and is radioactive.
IUPAC	(abbr). International Union of Pure
	and Applied Chemistry. Standardised
	naming conventions for chemicals.

J

joule	(n). Unit of energy.

K


kelvin	(n). Unit of temperature, with
	absolute zero being the point where
	no molecular motion occurs, at
	-273,15˚C. Hence, the freezing point
	of water is 273,15 K. Note that there
	is no degree sign before K.
ketone	(n). An organic compound with the
	carbonyl group = C = O. Made by
	oxidising secondary alcohols. E.g.
	acetone.

L


law	(n). In Physical Science, a
	formula or statement, deduced
	(discovered) from observation
	(watching). The formula or
	statement will then predict that
	under the same conditions the
	same thing will always happen. E.g.
	the first law of thermodynamics
	says that matter and energy
	cannot be destroyed, but only
	changed from one form to another.

leach	(v). When a substance drains out
	of soil, e.g. into rivers. Similar to
	“leak”.
litmus	(n). A type of acid/base indicator.
	See indicator. It is red when
	exposed to acid and blue when
	exposed to a base.

M

macromolecule	(n). A large molecule, usually a
	polymer or protein.
macroscopic	(adj). Large enough to be visible
	to the unaided human eye; big
	enough to be seen.
magenta	(n). A bright purple/pink colour.
manipulate	(v). To change, or rearrange
	something. Usually in Mathematics
	it means to rearrange a formula to
	solve for (to get) an answer.
material	(n). Any substance, not just cloth.
matter	(n). Substance; stuff. Opposite of
	vacuum (nothing).
mean	(n). See average.
median	(n). Mathematics: the number in
	the middle of a range of numbers
	written out in a line or sequence.
metal	(n). A substance which is malleable
	(can be hammered flat), is ductile
	(can be drawn into a wire), which
	conducts electricity and heat well
	and which is reflective (most light
	striking it is emitted again). Most
	elements are metals except the
	few on the right hand side of the
	periodic table starting at Boron (B)
	and running diagonally down to
	Astatine (At).
meth-	(prefix). Having one carbon. See
	formic.
methylated	(adj). Having had a single carbon
	or methyl group added.
metric	(adj). A measurement system,
	using a base of 10 (i.e. all the
	units are divisible by 10). The USA
	uses something known as the
	Imperial system, which is not used
	in science. The Imperial system is
	based on 12. Examples: 2,54 cm
	(metric) = 1 inch (imperial).
	1 foot = 12 inches = approx.
	30 cm; 1 metre = 100 cm. 1 Fl.Oz
	(fluid ounce) = approx 30 mℓ.
microscopic	(adj). Too small to be seen by the
	unaided human eye.

minimum	(n). The smallest amount possible.
mixture	(n). When you mix or combine
	substances without them
	undergoing a chemical reaction. In
	other words, the substances mixed
	stay separate (chemically) and do
	not bond. Different to compound.
	See compound, reaction.
modal	(adj). Pertaining to the mode, or
	method. Can mean: about the
	mathematical mode or about the
	method used. See mode.
mode	(n). Mathematics: the most
	common number in a series of
	numbers. See also mean, median.
mol	(abbr). Mole.
molar	(adj). About a mole. See mole.
mole	(n). A unit describing an amount
	of substance. 6,023 × 1023
	molecules or atoms of the
	substance.
	E.g. 18 g of water is 1 mol of
	water (H = 1, O = 16, H₂O = 18).
molecular	(adj). About molecules. See
	molecule.
molecule	(n). The smallest amount of a
	compound; a single particle
	composed of the elements that
	make up the compound. E.g. in
	water, a single particle consisting
	of two hydrogen atoms and one
	oxygen atom.
mono-	(prefix). One.
monomer	(n). Part of a macromolecule; the
	simplest repeating unit. Monomers
	bond to form polymers. See
	polymer, isomer.
monoprotic	(adj). Having one proton.

N

neutral	(adj). Chemistry: pH 7,0. Neither
	acid nor base. E.g. water. In
	common use: not biased. See bias.
neutralise	(v). To make something neutral; to
	complete an acid/base titration.
neutron	(n). A subatomic particle with
	no charge, mass approximately
	the same as a proton, found in the
	nucleus of an atom. Symbol n0.
	If there are too many protons in
	a nucleus, the substance will be
	radioactive as it releases
	alpha particles (helium nuclei,
	2p+ + 2n0).

nitrate	(n). Containing NO −.
	3
nitrite	(n). Containing NO −.
	2
nomenclature	(n). A system of describing things;
	a naming system, designed to
	make a name unambiguous or
	unique.
nonmetal	(n). Any of the elements that are
	not metals, e.g. Boron (B), Silicon
	(Si), Sulphur (S), Oxygen (O), etc.
nucleus (sing),	(n).The centre of something
nuclei (pl),	(generally), specifically the centre
nuclear (adj)	of an atom, consisting of at least
	one proton (hydrogen), or two
	protons and two neutrons (helium).
	Plural nuclei is pronounced “noo-
	klee-eye”.
numerator	(n). The opposite of a denominator;
	the number on top in a fraction.

O

-oate	(suffix). An ester.
odour	(n). A smell.
optimal	(adj). Best, most.
organic	(adj). Containing carbon, except C,
	CO, CO₂.
origin	(n). Mathematics: the centre of
	a Cartesian coordinate system.
	General use: the source of
	anything, where it comes from.
outlier	(n). Statistics: a data point which
	lies well outside the range of
	related or nearby data points.
oxalic (acid)	(n). Ethanedioic acid; chem.
	formula: (COOH)₂.
oxidation	(n). Specifically, adding an oxygen
	atom to a molecule, but more
	general use: losing electrons from
	any substance in a redox reaction.
	See redox.
oxide	(n). A compound containing
	an oxygen atom, especially if it
	previously did not contain one, e.g.
	iron (metal), vs iron oxide (rust).
oxidise	(v). To add an oxygen or remove
	electrons from a substance.

P

paraffin	(n). Any waxy organic substance,
	previously the general name for
	alkanes. Formula ranges from
	^C20^H42 ^{to C}40^H82^.

parallel	(adj). Keeping an equal distance
	along a length to another item
	(line, object, figure). Mathematics:
	two lines running alongside each
	other which always keep an equal
	distance between them.
particle	(n). Any small part, e.g. a proton,
	an atom, a molecule.
pascal	(n). The unit of pressure,
	abbreviated Pa, units: N/m2
pent-	(prefix). Five.
per	(prep). For every, in accordance
	with. Chemistry: the maximum
	amount of an element possible
	for the number of bonds available.
	See e.g. peroxide.
peroxide	(n). H₂O₂.
perpendicular	(adj). Normal; at right angles to
	(90˚).
phase	(n). Time, period; a state of matter
	(solid, liquid, gas); the relationship
	in time between the cycles of a
	system (such as an alternating
	electric current or a light or sound
	wave) and either a fixed reference
	point or the states or cycles of
	another system with which it
	may or may not be synchronised
	(simultaneous). I.e. if two systems
	vibrate at the same time at the
	same rate, they’re “in phase”.
photosynthesis	(n). The process of converting
	CO₂ into carbohydrates using
	atmospheric CO₂, chlorophyll, and
	light.
pi	(n). π, the Greek letter p, the
	ratio of the circumference of a
	circle to its diameter. A constant
	without units, value approximately
	3,14159.
plastic	(n., adj.). An artificial substance
	made from hydrocarbon polymers
	which is often flexible and able to
	be moulded and is often a poor
	electrical conductor (n); flexible
	(adj).
plot	(v). To place points on a Cartesian
	coordinate system; to draw a
	graph.
poly-	(prefix). Many.
polyester	(n). A polymer made from esters.
polymer	(n). A synthetic substance made
	from many monomers (repeating
	units). See monomer.
polymerisation	(n). Making a polymer.
polyprotic	(adj). Having many protons.

porous	(adj). Having many holes that allow
	fluids through.
positive	(adj). Having many protons not
	paired with electrons; a lack of
	electrons.
potential	(n). Having the ability to do work, in
	particular, E_p (potential energy, the
	tendency to fall or start moving,
	as in a spring), or emf (voltage).
	General use: potential exists when
	there is an energy difference
	between two points, e.g. due to
	gravity or electrical charge. In the
	context of electricity, read it as
	“voltage”.
precipitate	(n). Chemistry: A product of a
	reaction that cannot dissolve in the
	solution and settles at the bottom
	of the reaction vessel (container).
predict	(v). General use: to foresee.
	Physical Science: to state what will
	happen, based on a law. See law.
pressure	(n). A continuous force exerted on
	an object over a certain area, in
	pascals, Pa. N/m2. See pascal.
product	(n). Chemistry: the substance or
	compound made as a result of a
	chemical reaction. See reaction.
	Mathematics: the result of
	multiplying two numbers.
project	(n. & v.). A project (n., pronounced
	PRODJ-ekt) is a plan of action
	or long-term activity intended to
	produce something or reach a goal.
	To project (v., pronounced prodj-
	EKT), is to throw something, or to
	guess or predict (a projection). To
	project a result means to predict a
	result. See extrapolate.
prop-	(prefix). Three carbons.
	Pronounced “prope” (rhymes with
	“rope”).
proportion	(n). To relate to something else
	in a regular way, to be a part of
	something in relation to its volume,
	size, etc; to change as something
	else changes. See correlate and
	respectively.
protein	(n). A large, complex organic
	molecule containing nitrogen,
	usually making up structural
	elements of living things (building
	blocks of cells, antibodies, etc).
protolytic	(adj). Capable of removing a
	proton; proton transfer. Compare
	acid.

proton	(n). The positively-charged particle
	that forms the centre of an atomic
	nucleus, weighing 1 836 times as
	much as an electron, but having
	the same and opposite charge.
	Symbol p+. See also nucleus,
	neutron, electron.
pump	(n). A machine that uses energy
	to transfer a fluid from one
	place to another. In Biology one
	finds cellular pumps, which are
	biological machines for transferring
	ions and nutrients.
pure	(adj). Containing only the
	compound or element in question,
	without any other compounds or
	elements mixed in. See impure.
purification	(n). The process of removing
	impurities. See distil.

Q

qualitative	(adj). Relating to the quality
	or properties of something. A
	qualitative analysis looks at
	changes in properties like colour,
	that can’t be put into numbers.
	Often contrasted with quantitative.
quantitative	(adj). Relating to, or by comparison
	to, quantities. Often contrasted
	with qualitative. A quantitative
	analysis is one in which you
	compare numbers, values and
	measurements.
quantity	(n). Amount; how much.

R

rancid	(n). Having an unpleasant smell due
	to having started to ferment or rot,
	usually said of meat, oil or butter.
random	(n). Unpredictable, having no cause
	or no known cause. Done without
	planning.
range	(n). Mathematics: the set of values
	that can be supplied to a function.
	The set of possible y-values in a
	graph. See domain.
rate	(n). How often per second (or per
	any other time period). Physics:
	number of events per second; see
	frequency.

ratio	(n). A fraction; how one number
	relates to another number; exact
	proportion. If there are five women
	for every four men, the ratio of
	women to men is 5:4, written
	with a colon (:). This ratio can be
	represented as the fraction 5/₄ or
	1¼ or 1,25; or we can say that
	there are 25% more women than
	men.
react	(v). Chemistry: when two or more
	elements or compounds are
	brought into a mixture and form
	chemical bonds, creating new
	compounds.
reactant	(n). A chemical before it bonds with
	another chemical. See reagent.
reaction	(n). Chemistry: The process
	of reacting; a state in which
	chemicals react. See endothermic
	and exothermic. Physics (nuclear):
	When a nucleus of an atom breaks
	down and subsequently releases
	energy and/or bonds with another
	nucleus. In the first case, it is a
	fission (splitting) reaction, in the
	second case a fusion (joining)
	reaction.
reactive	(adj). Tending to react easily.
reactivity	(n). How reactive a substance is
	(unreactive or reactive).
reagent	(n). A reactant when it is still in its
	bottle or container, before being
	mixed.
redox	(abbr). Chemistry: reduction-
	oxidation reaction; a chemical
	reaction in which one substance
	is reduced (gains electrons), and
	another is oxidised (loses electrons).
	See reduce, oxidise, anode, cathode,
	electrode, electrochemistry.
reduce	(v). To make smaller. Chemistry: to
	gain electrons (negative charges).
reflux	(n., v.). A substance that flows back
	into its container after coming out.
	Chemistry: the process of boiling a
	liquid so that any vapour is liquefied
	and returned to the stock (source).
refraction	(n). Bending light when it travels
	from one medium (e.g. air) into
	another medium (e.g. water or
	glass). Changing the direction of
	propagation of any wave as a result
	of its travelling at different speeds at
	different points along the wave front.
	See Huygens’ principle, diffraction.

S


salt	(n). In common usage, NaCℓ.
	Chemistry: any compound formed
	from the reaction of an acid with
	a base, with the hydrogen of the
	acid replaced by a metal or other
	cation. A non-metal ion bonded to
	a metal ion.
saturated	(adj). Organic chemistry: Having
	no available bonds or only single
	bonds. Common use: cannot take
	any more, usually said of a cloth
	and liquid.
SI	(abbr). Système International. The
	international system of metric
	units used by scientists. See
	metric, IUPAC.
simplify	(v). To make simpler. Mathematics:
	to divide throughout by a common
	factor (number or algebraic letter)
	that will make the equation easier
	to read and calculate.
slaked (lime)	(n). Calcium Hydroxide, Ca(OH)₂.
solubility	(n). How easily something dissolves
	(mixes into a liquid).
soluble	(adj). See solubility.
solute	(n). The substance that you place
	in a liquid (the solvent) so as to
	dissolve it. E.g. salt. See solvent.
solution	(n). A mixture of a solute and a
	solvent. A liquid which has had
	something dissolved in it (mixed).
	Mathematics: the step-by-step
	displaying of calculations to
	arrive at answers. Common use:
	the answer to a problem, in the
	sense of dissolving (removing) a
	problem.
solvent	(n). The liquid that dissolves the
	substance placed into it. E.g. water.
spectator	(n). Chemistry: a compound or
	chemical which does not get
	involved in a chemical reaction.
spontaneous	(adj). Randomly, without
	provocation or cause or prior
	planning.
stable	(adj). Chemistry and Nuclear
	Physics: not likely to break down or
	react further.
standardised	(adj). Chemistry: a solution of
	known concentration, e.g. 1 molar
	(1 mol/dm3).

steam	(n). Water vapour, microscopic
	droplets of water. Not a gas, a
	suspension of water droplets in air.
	See suspension, gas, liquid, phase,
	aerosol.
STP	(abbr). Standard temperature and
	pressure; 101,3 kPa and 25˚C.
structural	(adj.). Pertaining to structure;
(isomer)	a series of molecules whose
	structures are different but their
	chemical or empirical formulae are
	the same.
sublimate	(v). To change phase of matter
	from solid straight to gas without
	the intermediate phase of liquid.
	See the case of dry ice (CO₂).
subscript	(n). A number placed below the
	rest of the line, e.g. CO₂.
substance	(n). Matter. Physical things.
substituent	(n). Chemistry: an ion or functional
	group or group of atoms that
	replaces a hydrogen on an organic
	molecule.
substitute	(v). To replace.
substitutents	(n). Something that gets replaced.
substitution	(n). The process of substituting.
	Mathematics: to replace an
	algebraic symbol in a formula with
	a known value or another formula,
	so as to simplify the calculation.
	See simplify. Chemistry: to
	cause a substituent to bond to a
	substance.
superscript	(n). A number placed above the
	rest of the line, e.g. πr2.
synthesis	(n). The process of
	manufacturing (making)
	something. Chemistry: to bond
	smaller molecules together
	to create a larger molecule,
	e.g. methanol from CO and H .
	Synthesis gas: a gas mixture ²
	(e.g. CO, H₂), which when heated
	produces a new compound, e.g.
	methanol.
synthetic	(adj). Artificial, man-made.
system	(n). Any closely associated and
	inter-related or inter-dependent
	group of things; a set of things
	working together. Chemistry: a
	vessel (container) which contains a
	chemical reaction.

T


terminal	(n). Final; end point.
termination	(n). Coming to an end.
tetra-	(prefix). Four.
theory	(n). A usually mathematical
	representation of an explanation
	for something in the sciences,
	which does not depend on the
	thing being explained. A theory
	differs from a law in that theories
	are prone to empirical (visible
	or measurable) refutation
	(rejection); meaning that they
	can be discarded if evidence
	comes in that they are wrong.
	See law.
thermoplastic	(n). Chemistry: will melt if heated.
thermoset	(n). Once set into a shape it cannot
	melt again.
thiosulphate	(n). A salt containing the anion
	S	O 2−.
	2	3
threshold	(n). Physical Science: the
	magnitude or limit of something,
	which, if exceeded, will cause
	something else, e.g. release of
	radiation, a chemical reaction, etc;
	the minimum amount of energy
	required to cause something.
	Medicine: the maximum safety
	level of a dose.
titrate	(v). To measure off a reagent
	precisely drop by drop into a vessel
	(container) containing another
	reagent, so as to work out the
	concentration of the reagent in the
	vessel.
toxic, toxin	(adj., n.). Poisonous, poison.
transfer	(n). To move from one place to
	another. Chemistry: usually refers
	to moving an electron from one
	compound to another. Finance:
	usually refers to a payment
	or credit. See credit, debit,
	transaction.
trends	(n). Mathematics: regular patterns
	within data.
tri-	(prefix). Three.
trial	(n). Chemistry: to repeat an
	experiment, an iteration,
	or particular attempt at an
	experiment. (From “try”, to try
	once).

triprotic	(n). Having three protons.
turbidity	(n). How muddy, muddled or
	opaque or disturbed a liquid is.

U

unit	(n). A subdivision of a scale. See
	scale.
universal	(n). A chemical which can indicate
(indicator)	how acid or basic a solution is,
	ranging from reds (acidic) to violets
	(basic), including most of the
	colour spectrum.
unsaturated	(n). Organic chemistry: having
	double or triple bonds present.
unstable	(n). Chemistry or Nuclear Physics:
	prone to disintegrating or reacting.
urea	(n). CO(NH₂)₂. The substance used
	to remove excess nitrogen from
	animals via urination. Useful as a
	fertiliser.

V


vapour	(n). The pressure above a liquid
pressure	caused by molecules evaporating
	from the surface of its liquid form,
	when in phase equilibrium (i.e. as
	many molecules leaving the liquid
	surface are condensing back into
	the liquid).
variable	(n., adj.). A letter used to represent
	an unknown quantity in algebra
	(n); a quantity that changes (n);
	subject to change (adj).

vessel	(n). Any container. Common use: a
	container or ship.
visible	(adj). Able to be seen by the human
	eye, opposite of invisible. Compare
	microscopic, macroscopic.
viscosity	(n). The thickness of a fluid. A
	viscous fluid flows slowly, e.g.
	syrup. Pronounced “viss-KOSS-
	itee” and “viss-k’s”.
volatility	(n). How easily something
	evaporates. E.g. Ether (C₂H₅OC) is
	more volatile than water.
volt	(n). Unit of potential difference
	in electricity. The difference of
	potential (E_p) that would carry one
	ampere of current against one
	ohm resistance. Same as emf. See
	emf, resistance, ohm, ampere.
voltage	(n). The measurement of volts.
voltaic	(n). The production of electricity
	in a cell. See battery, cell,
	electrochemistry, electrode,
	cathode, anode, galvanic.
volume	(n). A measure of the space
	occupied by an object, equal to
	length x breadth x height.

Y

yield	(n., v.). The amount of substance
	produced in a chemical reaction
	(n); products of a process (n); to
	hand over or give up (v).

The maths you need

This section gives you the basic mathematical skills that you need to pass any subject that makes use of mathematics. Whether you’re studying for Physical Science, Mathematics, or Mathematical Literacy, these basic skills are crucial. Do not go any further in this book until you have mastered this section.

1. Basic pointers

If a formula does not have a multiplication (×) sign or a dot-product (·), and yet two symbols are next to each other, it means “times”. So, m₁m₂ means mass 1 times mass 2. You can also write it as m₁ × m₂, or m₁·m₂
Comma means the same as decimal point on your calculator (i.e. 4,5 = 4.5). Do not confuse the decimal point with dot product (multiply): 4.5 = 4¹₂ but 4·5 = 20. Rather avoid using the dot product for this reason.
In science it is common to write divisors with an exponent. This means, for example, that 0,5 metres per second is usually written 0,5 m·s–1 rather than 0,5 m/s. Both notations are perfectly correct, however, and you may use either. It is important, however, that you either use –1 or / . If you just put 0,5 ms, that means 0,5 milliseconds, which is not a velocity (speed in a direction); it is a time. A variable is something that varies (means: changes). So, for example, the weather is a variable in deciding whether to go to the Variables in science and mathematics are represented with letters, sometimes called algebraic variables. The most common you see in maths is x, probably followed by y, z. In science, variables are given their letter symbols specifically depending on what they stand for; so, for example, M or m are used for mass (amount of substance in kilograms); v is used for velocity (speed in a certain direction); a is used for acceleration (change in velocity), etc. You can guess for the most part what a variable is for by what its letter is; so V is voltage, R is resistance, P is pressure, and so on.

2. Subject of formula or solving for
Very often you have to “make something the subject of a formula” or “solve for something”. This refers to finding the value of an unknown quantity if you have been given other quantities and a formula that shows the relationship between them.

Worked example 1
If John has 5 apples, and he gives some to Joanna, and he has two apples left, how many did he give to Joanna? Well, the formula would be something like this:

5 – x = 2

To solve for x, we simply have to swap the x and the 2. What we’re actually doing is adding “x” to both sides:

5 – x + x = 2 + x

this becomes:

5 = 2 + x

then we subtract 2 from both sides to move the 2 over:

5 – 2 = 2 – 2 + x
5 – 2 = x
3 = x … so John gave Joanna three apples.

The same procedures apply no matter how complex the formula looks. Just either add, subtract, square, square root, multiply, or divide throughout to move the items around.

Worked example 2
Let’s take an actual example from Electricity: V = IR. This means, the voltage in a circuit is equal to the current in the circuit times the resistance.
Suppose we know the voltage is 12 V, and the resistance is 3 Ω. What is the current?

V=IR
12=3 × I

divide throughout by 3 so as to isolate the I

12 = (30)I
3 ( 3 )

remember that anything divided by itself is 1, so:

12 = (1) × I … and 12 = 4 …so
3 3
4 = I or
I = 4 A … The circuit has a current of 4 amperes.

It is possible to remember how to solve for these equations using a triangle mnemonic as follows:
If you’re solving for V, cover V with your hand. Then, I next to R means I times R, or IR. So, V = IR. If you’re solving for R, cover R with your hand. V is over I. So R = ^V_I . While this is an easier way to do it, remember that many formulas do not consist of only three parts, so it is better to know how to make something the subject of a formula, or solve for something.
vir kghakjghd

Worked example 3
Here’s a more tricky example. Given

K_c = 4,5
[SO₃] = 1,5 mol/dm³[SO₂] = 0,5 mol/dm³[O₂] = (X – 48) mol/dm³

Solve for x:

∴x = 176 g

How did we get that answer?

Step by step
Let’s see how it works.First, solve for the exponents (powers):
step by tsep

Now we multiply both sides by 576 to remove the 576 from the bottom row

576 = (x – 48) 576
4,5   576

and we cancel the 576’s on the right hand side as shown above.
Now, if 576 ÷ 4,5 = 128, then

128 = x – 48

Now we add 48 to both sides to move the 48 across

128 + 48 = x – 48 + 48 … hence, 128 + 48 = x = 176.

3. Statistics
Many experiments in science use statistics. You should therefore at least know the following:
Dependent variable: The thing that comes out of an experiment, the effect; the results.
Independent variable(s): The things that act as input to the experiment, the potential causes. Also called the controlled variable.
Control variable: A variable that is held constant in order to discover the relationship between two other variables. “Control variable” must not be confused with “controlled variable”.
It is important to understand that in science, correlation does not mean causation. That is, if two variables seem to relate to each other (they seem to co-relate), it doesn’t mean that one causes the other. A variable only causes another variable if one of the variables is a function f(x) of the other. We will see more about this when we look at graphs, below.

Mean: The average. In the series 1, 3, 5, 7, 9, the mean is 1 + 3 + 5 + 7 + 9 divided by 5, since there are 5 bits of data. The mean in this case is 5.
Median: The datum (single bit of data) in the precise middle of a range of data. In the series 1, 3, 5, 7, 9, the median value is 5.
Mode: The most common piece of data. In the series 1, 1, 2, 2, 3, 3, 3, 4, 5, the mode is 3.

Often in scientific formulas it is said that things are proportional to each other. However, we cannot calculate the value of a force or energy output or mass etc., if we only know what things are in proportion (i.e. which things correlate).
Let’s take momentum for example. Momentum (how forcefully something moves, more or less), is proportional to velocity (speed in a direction). So the faster something’s moving, the more momentum it has. But p (momentum) can’t be calculated if we only know velocity; we need to know mass as well. Why? Because momentum is also proportional to mass; the more massive something is, the more momentum it has. Thus, to get rid of the proportionality sign (∝), we have to come up with a formula. Many experiments in science serve to find out what the relationship is between two variables, i.e. if they’re merely correlated — proportional — or if they’re causally related. In the case of momentum, it’s easy, because there are no further variables: p = mv. However, in the case of gravity or electric or magnetic field strengths, it’s not that easy. In those cases, we have to introduce something called a “constant”. A constant is a fixed value that is always multiplied into an equation. Constants are often written k. However, some specific constants, such as in the Law of Gravity, have their own symbol, in this case, G. These constants are given in the tables later in this book.

4. Graphs
A lot of work in science involves interpreting graphs. You get graphs of motion, graphs of rates of chemical reactions, graphs of distance-relative strengths of force fields, and so on. Before you can understand these graphs, it’s probably best to start from scratch with Cartesian Coordinates. “Coordinates” are numbers that refer to the distance of a point along a line, or on a surface, or in space, from a central point called the “origin”. Graphs that you will use have only two dimensions (directions). The positions of points on these graphs are described using two coordinates: how far across (left-to-right) the point is, called the x-coordinate, and how far up-or-down on the page the point is, called the y-coordinate.

Worked example 4
Consider the following graph. It shows six points in a straight line.

graphs
The coordinates shown can be described using what are called “ordered pairs”. For example, the furthest point in this graph is 3 units across on the “x-axis” or horizontal line. Likewise, it is also 3 units up on the y-axis, or vertical (up and down) line. So, its coordinates are (3;3). The point just below the midpoint or “origin”, is one unit down of the x-axis, and one unit left of the y-axis. So its coordinates are (-1;-1). Note that anything to the left or below of the origin (the circle in the middle), takes a minus sign. In most cases in science, you’ll only have graphs showing positive axes (plural of axis, pronounced aks-eez), since most graphs are of time
This series of dots look like they’re related to each other, because they’re falling on a straight line. If you see a result like this in an experimental situation, it usually means that you can predict what the next dot will be, namely, (4;4). This kind of prediction is called “extrapolation”. If you carry out the experiment, and find that the result is (4;4), and then (5;5), you’ve established that there is a strong relation or correlation. You can therefore start thinking about a formula to describe your findings. For example, this might be a graph showing a measurement of voltage (x) against a measurement of resistance (y).
Now, another way of saying that x relates to y, or x is proportional to y, is to say that y is a function of x. This is written y = f(x). So, in the example given above, voltage is a function of resistance. But how is y related to x in this graph? Well, it seems to be in a 1 to 1 ratio: y = x. So the formula for this graph is y = x. In this case, we’re only dealing with two factors; x and y. In other graphs you’ll find that sometimes more factors are involved, such as acceleration graphs, which have units of m/s2. Don’t worry about that; you treat them the same way (for example, m/s2 vs. time).

Worked example 5
Now, let’s take a slightly more complex case, illustrated next to this paragraph. In this graph, we see that wherever x is equal to something, y is one more. So, trace your finger from the bottom left dot upwards. It meets the x-axis at the point -3. Do the same for the same point towards the y-axis. You’ll see it meets the y-axis at -2. You’ll see the next coordinates are (–2;–1), then (–1;0), then (0;1), (1;2), and finally (2;3). From this we can see that whatever x is, y is one more. So, y = x + 1 is the formula for this line.
worked example 5 jgjad

Worked example 6
Let’s take another case. In this next case, we see the following values: where x has a certain value, y has double that value. Let’s tabulate it.
worked exapmple 6 jkayhgda

x	y
1,5	3
1	2
0,5	1
0	0
–0,5	–1
1	–2
–1,5	–3

So, when x is 1,5, y is 3, when x is 1, y is 2. Thus, the formula for this line is: y = 2x. This value next to x is called the “gradient” or “slope” of the line. The larger the value next to x is, i.e. the larger the gradient, the steeper the slope. The gradient is usually abbreviated as “m” when it is unknown.
Now, how this applies to science is simple: if we are looking, for example, at a case of a graph of a chemical reaction, we will usually have the x-axis as time. And the y-axis will usually be the quantity (amount) of substances produced. So, if we have a graph of a chemical reaction with a large gradient, it means that the reaction is fast; a lot of substance (y) i s produced in a short time (x). If, for example, we heated the reaction, and saw that the gradient increased even more, that would show that the chemical reaction was sped up by heat, or, that reaction rate is proportional to heat. Likewise, if the gradient sloped downwards, it would show that the reaction slowed down over time, because y, the amount of substance produced, was decreasing, as x (time) increased, e.g. because the reactants were being used up.

Worked example 7
Let’s do one more case. In this case, we can see that y is a function of x, since it’s a straight line graph. However, it’s not that easy to see the relationship between x and y. We can see that the slope is the same as the previous graph, so it must be something like y = 2x. However, it doesn’t quite make sense, since 2(–1,5) is not –2. We see that where x is zero (at the origin), y is at 1. But the slope is the same, so it must be y = 2(0) + 1. So the formula is: y = 2x + 1.
worked example 7 jygyuad

x	y	2x + 1
-1,5	-2	2(–1,5)+1 = –3+1 = –2
-1	-1	2(–1)+1 = –2+1 = –1
-0,5	0	2(–0,5) +1 = –1+1 = 0
0	1	2(0)+1 = 0+1 = 1
0,5	2	2(0,5)+1 = 1+1 = 2
1	3	2(1)+1 = 2+1 = 3

Resource sheets

The following information sheets will be supplied to you in the exam. You do not need to memorise them.

SI Units: Multipliers

Prefix	Symbol	Value	Value written in full
tera	T	10¹²	1 000 000 000 000
giga	G	10⁹	1 000 000 000
mega	M	10⁶	1 000 000
kilo	k	10³	1 000
hecto	h	10²	1 00
deka	da	10¹	1
deci	d	10^–1	0,1
centi	c	10^–2	0,01
milli	m	10^–3	0,00 1
micro	µ	10^–6	0,00 000 1
nano	n	10^–9	0,00 000 000 1
pico	p	10^–12	0,00 000 000 000 1
femto	f	10^–15	0,00 000 000 000 000 1

Constants

Name	SI Unit Symbol	Approximate Value	Easier to Understand
STP (Standard Temperature and Pressure), (in Physics).	not applicable, two conditions	1 ATM (101,3 kPa), 25°C (298 Kelvin (K))	You generally put two ATM (bar) pressure in car tyres, i.e. the pressure in a car tyre is twice atmospheric pressure
Standard Conditions (Chemistry)	not applicable, three conditions	STP plus 1 mol/dm₃	As above
Gas constant	R	8,3 J / mol⋅K	The R in PV = nRT
Molar gas volume at STP	V₀	22,4 dm3 / mol	22,4 Litres of gas is made by a mole of a substance
Avogadro’s constant	N_A	6,022045 × 10₂₃units/mol	6 022 000 000 000 000 000 000 00 particles is one mole

period table asdshbji

Formulas

Moles, Gas Laws, Chemical Equilibria:

= gas constant
= number of moles

m = mass
T= temperature
V= volume
c= concentration, also [ ]

n = m c = n c = m
M V MV
PV = nRT P₁V₁ = P₂V₂
T₁ T₂

formulas

Where [S] is the concentration of S in mol/dm₃Notes:
In most cases in chemistry, subscripts refer to how many atoms there are; e.g. H2O = two atoms of H & 1 atom of O.

Standard reduction potentials

Notes:

E_θ means the same as E₀.
There are two versions of this table; they are identical except one is upside-down. Just memorise that Fluorine (F) has the greatest oxidising ability.
A strong reducing agent will displace a weaker reducing agent from its salt.
Always start with the oxidation half reaction.
A redox reaction will take place when a reducing agent reacts with an oxidising agent.
Balance the electron charge of each half-reaction by multiplying each with a suitable coefficient.
Add the two half-reactions together, eliminating electrons from both sides.
Eliminate common ions or molecules from both sides of the equation e.g. H+ and H₂
You can then combine the E₀ voltages to get the total voltage of a cell. Use the values exactly as they are; do not round off.
- E⁰_cell = E⁰_cathode – E⁰_anodeOR
- ^E⁰cell ^{= E}⁰oxidising agent ^{– E}⁰reducing agent
A positive answer means that the reaction will proceed spontaneously from left to right. A negative value means that it is not spontaneous.

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GRADE 12 NOTES – PHYSICAL SCIENCE PAPER 2: CHEMISTRY STUDY GUIDES

Overview

Dear Grade 12 learner

How to use this study guide

Top 10 study tips

Mnemonics

Mind maps

On the day of the exam

Question words to help you answer questions

Vocabulary

General terms

Technical terms

The maths you need

Resource sheets

Formulas

Standard reduction potentials

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