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

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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 levelDescriptionPaper 2
(Chemistry)
1Remembering/Recall15%
2Understanding/Comprehension40%
3Applying and analysing35%
4Evaluating and creating (synthesis)10%
PaperType of questionsDurationTotalDateMarking
2Chemistry

  • 10 multiple-choice questions – 20 marks
  • Structured questions – 130 marks
3 hours150October/NovemberExternal
Paper 2: Chemistry Focus
ContentMarksTotalDurationWeighting of cognitive levels
Chemical change84150 marks3 hours15403510

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

  1. Have all your materials ready before you begin studying – pencils, pens, highlighters, paper, etc.
  2. 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.
  3. 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.
  4. 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.
  5. Keep your study sessions short but effective and reward yourself with short, constructive breaks.
  6. Teach your concepts to anyone who will listen. It might feel strange at first, but it is definitely worth reading your revision notes aloud.
  7. Your brain learns well with colours and pictures. Try to use them whenever you can.
  8. 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.
  9. Repetition is the key to retaining information you have to learn. Keep going – don’t give up!
  10. 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

  1. 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.
  2. Arrive on time, at least one hour before the start of the exam.
  3. Go to the toilet before entering the exam room. You don’t want to waste valuable time going to the toilet during the exam.
  4. 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.
  5. 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.
  6. Try all the questions. Each question has some easy marks in it so make sure that you do all the questions in the exam.
  7. Never panic, even if the question seems difficult at first. It will be linked with something you have covered. Find the connection.
  8. 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.
  9. Write big and bold and clearly. You will get more marks if the marker can read your answer clearly.
  10. 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 wordWhat is required of you
AnalyseSeparate, examine and interpret
CalculateThis means a numerical answer is required – in general, you should show your working, especially where two or more steps are involved
ClassifyGroup things based on common characteristics
ComparePoint out or show both similarities and differences between things, concepts or phenomena
DefineGive a clear meaning
DescribeState in words (using diagrams where appropriate) the main points of a structure/process/phenomenon/ investigation
DetermineTo calculate something, or to discover the answer by examining evidence
DifferentiateUse differences to qualify categories
DiscussConsider all information and reach a conclusion
ExplainMake clear; interpret and spell out
IdentifyName the essential characteristics PAY SPECIAL ATTENTION
LabelIdentify on a diagram or drawing
ListWrite a list of items, with no additional detail
MentionRefer to relevant points
NameGive the name (proper noun) of something
StateWrite down information without discussion
SuggestOffer an explanation or a solution
TabulateDraw 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

TermMeaning
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
ableexchanged 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). -CO32–
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,
Principlechemical 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
tionhydrogen from a substance.
dehydrohalo-(n). To remove hydrogen and a
genationhalogen 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
chemicalcause 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 (Ek), 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.
equilibriumChemistry: 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
extrusiona 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
ationatom 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). HO+ 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
C20H42 to C40H82.
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, Ep (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
SO 2−.
23
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
pressurecaused 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 (Ep) 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 = VI ​. 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

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

Solve for x:

  • kc kbhkajghd
    ∴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

xy
1,53
12
0,51
00
–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

 x2x + 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

PrefixSymbolValueValue written in full
teraT10121 000 000 000 000
gigaG1091 000 000 000
megaM1061 000 000
kilok1031 000
hectoh1021 00
dekada1011
decid10–10,1
centic10–20,01
millim10–30,00 1
microµ10–60,00 000 1
nanon10–90,00 000 000 1
picop10–120,00 000 000 000 1
femtof10–150,00 000 000 000 000 1

Constants

NameSI Unit SymbolApproximate ValueEasier to Understand
STP (Standard Temperature and  Pressure), (in Physics).not applicable, two conditions1 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 conditionsSTP plus 1 mol/dm3As above
Gas constantR8,3 J / mol⋅KThe R in PV = nRT
Molar gas volume at STPV022,4 dm3 / mol22,4 Litres of gas is made by a mole of a substance
Avogadro’s constantNA6,022045 × 1023 units/mol6 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/dm3
Notes:
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

standard reduction potential hufthtugfad

Notes:

  • Eθ 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.
    • E0cell = E0cathode – E0anode
      OR
    • E0cell = E0oxidising agent – E0reducing 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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