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TOPIC 1: Key Concepts in Chemistry
➢ FORMULAE, EQUATIONS & HAZARDS
 During a chemical reaction, bonds between atoms break as they rearrange themselves to form
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different chemicals
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Word equations are used to show what happens in a chemical reaction using the full names (e
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magnesium + oxygen –> magnesium oxide)
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g
...

Equations must always be balanced so the equation shows the same number of atoms on each side
...

State symbols can be added to tell you the physical state of the reactants & products, including solid
(s), liquid (l), gas (g) & aqueous (aq – dissolved in water)
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If there is fizzing, a gas is being formed
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HOW TO WRITE IONIC EQUATIONS:
1
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2
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3
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4
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Hazards are anything that can cause harm – whereas risks are the probability associated of someone
being harmed after exposure
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Hazards symbols are found on chemical containers to highlight dangers & allow you to work safely
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Oxidising: provides oxygen allowing other material to catch fire burn more fiercely SO they
must be kept away from flammable substances, skin & clothes
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Highly flammable: catches fire easily SO they must be kept away from open fires, skin & clothes
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Environmental hazard: harmful to organisms & environment SO it must be disposed of
properly & not into environment
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Corrosive: destroying living material, including living tissue, SO never let it meet skin, eyes or
clothes
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Toxic: could cause death by absorption, swallowing or inhaling SO never let it meet skin or
inhale it
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Harmful: can cause irritation, blistering or reddening of skin SO keep away from skin, eyes &
clothes
...
JOHN DALTON: described atoms as solid spheres, where different spheres are made up of
different elements
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JJ THOMSON: (concluded atoms were not solid spheres) his measurements of charge & mass
lead to the discovery of the smaller, negatively charged particles – electrons
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3
...
They
expected to particles to pass or be slightly deflected, since the positive charge was spread out
...
He also believed there
was a ‘cloud’ of electrons surrounding it, so most of the atom was empty space
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NIELS BOHR: (realised a ‘cloud’ of electrons would be attracted to the nucleus & cause the
atom to collapse) he proposed a new nuclear model with electrons orbiting the nucleus with
fixed shells, where each shell has a fixed energy
...
Further experiments by Rutherford & others showed that the nucleus could be divided into
smaller particles – they were referred to as protons
...
JAMES CHADWICK: carried out experiment to provide evidence for neutral particles in the
nucleus – they became known as neutrons
...

Subatomic particles have a relative mass measured in mass number units (amu) where protons &
neutrons have a mass of 1 & an electron have a mass of 1/1840
...
The nucleus (made of neutrons & protons) is in the
centre & it is orbited by electrons in shells
...

Electrons are tiny & negatively charged but their shells cover a lot of space – their size is determined
by the size of the atom
...
However, if electrons are added or
removed, they become ions because they become charged
...

Isotopes are atoms of the same element with the same number of protons but different number of
neutrons (e
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carbon-12 where the mass number is 12)
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As neutrons as neutrally charged, the atoms remain neutral
...
This is the average mass
of one atom of the element compared to 1/12 the mass of one atom of carbon-12
...

When an element has different isotopes, they occur in different abundances or percentages so you
must use an equation to calculate the Ar
...
e
...
He realised, by putting them in order of atomic mass, a
pattern appeared, & element of similar chemical properties could be put in columns
...
Wherever this happened, he switched the order of elements
...
When they were found & fitted, it confirmed his ideas
...
Modern periodic
tables show elements in order of ascending atomic number (same pattern as Mendeleev)
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 Electrons occupy shells/ energy levels with the lowest fill first (closet to nucleus)
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When the shells are filled, they are stable
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 Electronic configurations show the arrangement of electrons in an atom
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g
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8
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Using the period & group number from the periodic table
can ensure accuracy from the number of shells to the number of electrons on the last shell
...


➢ BONDING & TYPES OF SUBSTANCE
 Ions are charged particles formed when atoms lose or gain electrons
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 The number of electrons lost or gained is the same as the charge on the ion
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 The number of electrons they transfer is dependent on the number of the electrons on the outer
shell – which is also their group number
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 Metals have less electrons on their outer shell, so it is easier for them to lose than gain electrons
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g
...

 After ionic bonding, some chemicals change their name, including: polyatomic ions (Hydroxide
(OH-), Nitrate (NO3-), Carbonate (CO32-), Sulfate (SO42-)), part of group 6 & all of group 7
...
If they
end in ‘-ide’, they are negative ions with one element
...

 The strong electrostatic attraction between the oppositely charged ions holds the ions together
...
You show the charges as +
or – next to the big square bracket for every labelled ion involved
...

 Giant ionic lattice can represented in many way, including: dot & cross diagrams (useful to show
how its formed & where electrons come from – but it doesn’t show the structure, relative size or
arrangement), 3D models (useful to show relative size & regular pattern in ionic crystal – but it only

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lets you see the outside) & ball & stick model (useful to show regular pattern, arrangement & how
crystal extends further – but it suggests there are gaps between the ions)
...

Most ionic compounds dissolve easily in water
...
However, when melted or dissolved, the ions are free to move & carry electric charge
...

There is a strong electrostatic attraction between the positively charged nuclei of each atom & the
negatively charged pair of electrons
...

Covalent bonds can also be represented in many ways, including: dot & cross diagram (useful for
showing where the electron comes from – but not the relative size or arrangement in shape),
displayed formulas (useful to show what atom contain & the connections – but it doesn’t show the
relative size, 3D structure or where the electrons come from) & 3D model/ ball & stick models
(useful to show arrangement in space, shape & bonds– but it doesn’t show the relative size or where
the electrons come from & suggests there are gaps)
...

Covalent substances cannot conduct electricity because there are no ions or delocalised electrons to
carry an electrical charge
...

This is because the atoms within the small molecules have strong covalent bonds, but there is only a
weak intermolecular force between the molecules (this is easy to overcome)
...

Giant covalent structures are made up of lots of atoms covalently bonded strongly in a lattice
structure; hence they have high melting & boiling points & are not soluble in water
...

Graphite is used for lubricating & electricity; graphene is added to composite material to add with
strength without weight; diamond is used for strengthening cutting tools; & fullerenes are used in
medicine (drug delivery), catalysts & strengthening materials
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It is drawn as displayed formula – where the monomer has brackets
around it with bonds through it & a small ‘n’ in the bottom left corner
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There is a
strong electrostatic attraction between the positively charged metal ions & delocalised electrons
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Delocalised electrons carry charge & thermal energy through the structure
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They are very dense as the ions are closely packed
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g
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➢ CALCULATIONS INVOLVING MASSES
 Relative formula mass (Mr) is the sum of the relative atomic mass of all the atoms within a
compound
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g
...
5))
...

 HOW TO CALCULATE EMPIRICAL FORMULA:
1
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2
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Rewrite empirical formula
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 HOW TO CALCULATE MOLECULAR FORMULA:
1
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2
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3
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 Without the molecular formula, you can still calculate the empirical formula using the masses of
elements from the compound
...
Find Ar of all elements in the compound (using periodic table)
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Find relative amount (mole) of each element by dividing its mass (or percentage) by its Ar
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Write relative amount of each element as a ratio
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Divide each number in the ratio by the smallest number to find 1: x ratio
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Find nearest whole number ratio & write empirical formula
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g
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 HOW TO USE EXPERIMENTS TO FIND EMPIRICAL FORMULA:
1
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(heat before to remove any traces of oil & water)
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Add magnesium ribbon (cleaned with emery paper) & reweigh
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Heat crucible with magnesium, leaving a small gap for oxygen to enter
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Heat strongly until magnesium ribbon is white (full reacted)
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Allow crucible to cool, then reweigh
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Using mass of magnesium & oxygen, find the empirical formula of magnesium oxide
...

 You can see the conservation of mass if you do a reaction in a closed system over a mass balance
(e
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precipitation reaction) to show how the mass does not change
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 You can use the idea of the conservation of mass to calculating reacting masses (individual reactants
& products)
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If
all the reactants are not gas, but some the products are & can escape the reaction vessel, the mass
will decrease (e
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when CO2 gas is formed after thermal decomposition)
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g
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 Concentration is the amount of solute dissolved in a solvent to form a solution
...

 CALCULATING CONCENTRATION:
concentration (g/ dm3) = mass (g)/ volume (dm3)
 If you know the balanced equation & the mass of one other substance, you can calculate the mass
of another reactant or product
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Write out the balanced equation
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Work out Mr of elements you are interested in
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For substance you know the mass of, find relative amount (mole) of each element by dividing its
mass by its Mr
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Using balanced equation, work out relative amount (mole) of the other substance
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Multiply relative amount (mole) by Mr to give mass of that substance
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The limiting reactant is directly proportional to the
amount of product formed (if the other reactants are in excess)
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02 x 1023)
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 One mole (6
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g
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02 x 1023 particles
of carbon weighs 12g)
...
of particles (atoms, molecules, or ions) = no
...
02 x 1023)
 CALCULATING AMOUNTS OF SUBSTANCES:
no
...

 The molar ratios can be used to work out how many moles of a reactant or product is involved (if
some information is given about another substance) or you can find the molar ratios using the
reacting masses (& products)
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Work out Mr of elements involved
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Divide mass of each substance by Mr to find number of moles
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Divide number of moles of each substance by smallest number of moles in reaction
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If any numbers are not whole number, multiply all number by the same number
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Write balanced symbol equation by molar ratios as balancing number
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The state of the material is dependent
on the strength of the force of attraction between the particles of the material
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 A model known as the particle model explains how particles in each state of matter behave – where
each particle is visualised as a small, solid, inelastic sphere
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The particles do not have much energy, so they do
not move, hence they keep a definite shape & volume
...

 For liquids, the forces of attraction are weaker, so they are randomly arranged & move freely past
each other
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They keep a definite volume (fill a container from the
bottom), but not shape
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It also expands
...
The particles are also in random motion & move
freely past each other
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The particles are very far apart & mostly empty space, so it fills
any container & do not keep a definite shape or volume
...
This causes pressure to increase or, if there is
no lid, the volume increases
...

 Changes of state are known as physical changes, since only arrangement or energy changes (not
particles) – they can be undone by heating (melting & boiling) or cooling (freezing & condensing)
...
At melting point, particles have enough energy to
break free & become liquid) & boiling (heated: gains energy, moves more, & weakens forces
...

 They are 2 physical changes from giving out heat, including: freezing (cooled: liquid does not have
enough energy, less free to move, & cannot overcome force
...
At boiling point, force is strong
enough to become a liquid)
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 Chemical changes are different to physical changes because bonds break & atoms change places to
form different substance (reactants to products)
...

 To predict the state of a substance at a certain temperature, remember that below melting point is
solid, above boiling point is gas & between the two points is liquid
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 A pure substance contains one compound or element throughout (fixed composition) – otherwise,
it is a mixture
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 When testing for purity, you can measure melting point of sample using melting point apparatus
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If the melting point is the same as from the data book, it is pure
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 HOW TO PERFORM SIMPLE DISTILLATION (e
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saltwater or ink):
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3
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4
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5
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 You can use anti-bumping granules to prevent formation of large bubbles & liquid boiling over
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 HOW TO PERFORM FRACTIONAL DISTILLATION (e
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crude oil):
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2
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3
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4
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When thermometer matches boiling point, it has
reached the top & passed into condenser to cool
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Liquids with higher boiling points may also evaporate, they only get part way before condensing
& runs back down (coolest at the top of the column)
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When first liquid is collected, you increase temperature to next lowest boiling point
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 Filtration is used when your desired product is an insoluble liquid (in a liquid mixture) or to purify
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Fold filter paper into cone & place in filter funnel (in neck of conical flask)
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Pour mixture into funnel (making sure it does not down the side of the filter paper)
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Liquid (filtrate) will filter through & leave behind solid (residue) in filter paper
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 HOW TO PERFORM CRYSTALLISATION:
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3
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4
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5
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 Chromatography is used to separate a mixture of soluble substances & identify them
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 Mobile phase (liquid solvent) passes over stationary phase (filter paper); components in mixture
separate out, causing them to be in all different places
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They produce a spot on
a chromatogram
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 HOW TO PERFORM PAPER CHROMATOGRAPHY (e
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dyes in ink):
1
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2
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Amount of time spent in each phase (& hence the distance the molecules travel) is based on how
soluble it is in the solvent & how attracted they are to the paper
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Some chemicals are colourless & require a locating agent sprayed on it for it to show up
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CALCULATING Rf VALUE (2 decimal places between 0 & 1):
Rf value = distance travelled by solute/ distance travelled by solvent
Paper chromatography is normally carried out to see if a certain chemical is present in a substance
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Pure substances would not be separated by a paper chromatography, unlike a mixture
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HOW TO PURIFY WATER FOR DRINKING:
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4
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Sea water can be distilled to provide potable water by simple distillation; however, it is very
expensive as it requires a lot of energy
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TOPIC 3: Chemical Changes
 pH is a measure of how acidic or alkaline a solution is (using a pH meter/ probe) from 0-14
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 Anything less than 7 is acidic (lower the pH, more acidic) & they release H+ (hydrogen) ions;
anything more than 7 is alkaline (higher the pH, more alkaline) & they release OH- (hydroxide) ions;
& neutral solutions have a pH of exactly 7
...

 When the concentration of hydrogen ions in solution increases, it is more acidic (lower pH); when
concentration of hydroxide ions increases, it is more alkaline (higher pH)
...
You must add a few drops then consult its pH chart
...
During the reaction, hydrogen ions from the acid react with the
hydroxide ions from the base to produce water (H+(aq) + OH-(aq) –> H20(l))
...
This can be proven with an indicator
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Measure out 150cm3 of dilute hydrochloric acid into a conical flask using a measuring cylinder
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Measure 0
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3
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4
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5
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This involves them producing hydrogen ions & another (negatively charged) ion
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 Strong acids with pH 0-2 (hydrochloric – HCl(g) –> H+(aq) + Cl-(aq), nitric – HNO3(l) –> H+(aq) +
NO3-(aq), & sulfuric acid – H2SO4(l) –> H+(aq) + SO42-(aq)) ionise almost completely (most acid
particle dissociate to release a hydrogen ion
...

 Ionisation/ dissociation of a weak acid is a reversible reaction – which sets up an equilibrium
between the dissociated & undissociated acid
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 While acid strength (strong or weak) tells you about the proportion of acid molecules that ionise in
water, the concentration (concentrated or dilute) is very different
...

 pH is dependent on the acid’s concentration of hydrogen ions
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g
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Hence, if concentration decreases by factor of 10, the pH
increases by 1
...
As bases, metal oxides/ hydroxide reacts with acids to form salt &
water (general equation: acid + metal oxide/ hydroxide –> salt + water)
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g
...

 When other metals react with acid, they produce metal salt & hydrogen gas (general equation acid
+ metal –> metal salt + hydrogen)
...
This can be proven with a hydrogen test – where you hold a lit
splint in the test tube until you hear a ‘squeaky pop’ sound
...

 When metal carbonates react with acid, they also produce a salt, water, & carbon dioxide gas
(general equation: acid + metal carbonate –> salt + carbon dioxide + water)
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 The cloudiness is a result of the formation of calcium carbonate
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 WHETHER A SALT IS SOLUBLE OR INSOLUBLE:
common salts of sodium, potassium & ammonium: soluble
nitrates: soluble
common chlorides: soluble (except with silver & lead)
common sulfates: soluble (except with lead, barium & calcium)
common carbonates & hydroxides: insoluble (except with sodium, potassium &
ammonium)
 Insoluble salt will form as a precipitate when two solution are mixed
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Add one spatula of soluble salt & some deionised water to dissolve it (shake)
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Repeat in a different test tube with another soluble salt
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Tip both solution into a small beaker & stir
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 Soluble salts are made by reacting an acid with a metal or insoluble base (metal oxide/ hydroxide/
carbonate)
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 HOW TO MAKE SOLUBLE SALTS FROM ACID & INSOLUBLE BASE (e
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copper sulfate)
(filtration & crystallisation):
1
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2
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3
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5
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Keep adding copper oxide until in excess & reaching bottom (neutralisation is done)
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Crystallise copper sulfate solution (filtrate) by heating in evaporating dish
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Filter out crystals & dry
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Instead, the alkali reactant is soluble
(unlike the base)
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Measure out set amount of acid into conical flask using a pipette, add some indicator & place on
a white tile
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Fill the burette with alkali & record the volume
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Slowly add alkali & swirl each time until indicator changes colour (acid has been neutralised)
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Read final volume left in burette to calculate volume needed to neutralise acid
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Then repeat reaction with exact same volume of acid & alkali (& no indictor) to produce an
uncontaminated salt
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Perform a crystallisation reaction to the solution of salt & water
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g
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 Electrolysis is when you break down a substance using electricity
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At the
electrodes, they react, & the ionic substance starts to decompose (e
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aluminium oxide into
aluminium & oxygen)
...

 The ionic compound cannot be solid because the ions are in fixed positions, but molten or
dissolved compounds have ions that can move freely & conduct electricity
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g
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 HOW ELECTROLYSIS WORKS:
1
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4
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5
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 Electrolysis always involves a redox (reduction & oxidation) reaction
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 Binary compounds are ionic compounds containing two elements (cation & anion) that are ions
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 Half-equations show how electrons are transferred during the reactions at the electrodes
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Write chemical symbol for positive ion on left hand side of equation
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Write chemical symbol for neutral atoms/ molecules produced on right-hand side
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Balance number of atoms in equation
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Balance charges by adding or subtracting electrons as e-
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Write chemical symbol for negative ion on left-hand side of equation
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Write chemical symbol for neutral atoms/ molecules produced on right-hand side
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Balance number of atoms in equation
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Balance charges by adding or subtracting electrons as e-
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 Sometimes, there will be more then two types of free ions in the electrolyte (e
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salt forms H+, OH& the ions from the salt) – then it depends on how reactive the elements involved are
...
g
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 H+ & OH- ions form in water when a water molecule dissociates (H2O(l) ⇌ H+(aq) + OH-(aq))
...

 HOW TO SET UP ELECTROLYSIS OF AN AQUEOUS SOLUTION:
1
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2
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3
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Then turn on power supply
...
g
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Electrical supply acts by removing
electrons from one electrode & adding it to the other
...

 You can increase the rate of electrolysis by increase the current (e
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adding more batteries)
...
It can be purified
using electrolysis with copper electrodes
...

 HOW TO PURIFY COPPER USING ELECTROLYSIS:
1
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2
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3
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 HOW TO SET UP ELECTROLYSIS OF AN MOLTEN/ MELTED SOLUTION:
1
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2
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3
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4
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TOPIC 4: Extracting Metal & Equilibria
➢ OBTAINING & USING METALS
 Oxidation & reduction have two definitions
...

 For example, a redox (& exothermic) reaction is combustion (when something is burnt is oxygen)
...

Reactive metals are easily oxidised (losing electrons & gaining oxygen) – they are less resistant
...

 Carbon is commonly included to dictate how the metal is extracted from its ore; also, hydrogen is
included to shows its reactivity with dilute acids
...
Also, you can measure the temperature change of the reaction
over a given time (use the same mass & surface area of each metal & same volume of liquid)
...

 If the metal is above hydrogen in the reactivity series, it will react with dilute acids
...
The reactivity is evident from the rate of
hydrogen gas production as bubbling (more reactive, faster reaction)
...
You test for hydrogen
using the ‘squeaky pop’ test; more reactive metals produce a louder squeaky pop
...

 Some metals form cations when they react with water
...
Less reactive metals do not react much with water – but they do with steam
...
Inside a test tube, place mineral wool soaked in water & metal
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On the end, close the test tube with a bung & tube
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Heat the mineral wool (to produce steam) & the metal
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Place lit splint by the bung to ignite hydrogen gas that is given off
...

 The final method to determining reactivity is reacting a metal with a salt solution (containing a
dissolved metal compound)
...
If you react a more
reactive metal with the solution of a less reactive metal salt, the more reactive metal would displace/
replace the other (if the metal is less reactive nothing will happen)
...
When the reaction
involves displaces a metal in a salt solution, the more reactive metal loses electrons/ is oxidised &
the less reactive metal gains electrons/ is reduced (shown using half equations)
...
The less reactive metal leaves the ionic & return to being an atom
...
g
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The rest are extracted from their ores (a rock
containing enough metal to profitable extract metal from)
...

 A metal below carbon in the reactivity series can be extracted by reducing it in a reaction with
carbon
...
The products are pure metal &
carbon dioxide (& some carbon monoxide)
...
Although, mining requires digging up large areas of land (eye-sore)
...
To extract the metal using electrolysis, you
must melt it down to become molten
...
This is expensive because metals have high
melting points & a lot of electricity is required
...

 The supply of some metal-rich ores is running low (e
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copper, but its demand is growing)
...
The new ways are bioleaching & phytoextraction – they are
cheap, require less energy & have a smaller environmental impact
...
It uses bacteria which convert metal compounds in the ore into
soluble metal compounds – thus, separating the metal from its ore
...
A
disadvantage is can produce a toxic substance (sulphuric acid) & it is slower
...
The plants cannot
get rid/ use the metal, so it builds up in the leaves
...
The ash with metal compounds (higher concentration than soil, so extractable quantity is
more reasonable) is used to extract by electrolysis or displacement
...

 Recycling uses waste material to make new products
...
Metals are also a finite resource), environmental benefits (burning fossil fuels contributes
to acid rain & climate change, mining causes noise pollution, damages environment & habitats &
landfill take up space & cause pollution), & economic benefits (cheaper than extract & creates jobs)
...

 HOW TO DO A LIFE CYCLE ASSESSMENT:

1
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2
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3
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g
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4
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➢ REVERSIBLE REACTIONS & EQUILIBRIA
 Reversible reactions are when the products of a reaction can react with themselves to produce the
original reactant
...

 If the reversible reaction occurs in a closed system, a state of dynamic equilibrium will be reached
...
Both reactions are happening, but the overall effect is nil (forward & backward
reaction cancel each other out)
...
This causes an increase in the concentration of products, so the backwards reaction
speeds up
...

 When a reaction is at equilibrium, the number of reactants & products are not always equal
...
If it lies to
the left/ backward reaction, the concentration of reactants is greater
...

 Le Chatelier’s principle is the idea of changing the condition of a reversible reaction at equilibrium
so the system will try to counteract the change – this allows any effects to be predicted
...

 HOW TO CHANGE THE POSITION OF EQUILIBRIUM:
1
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If you lower the temperature, equilibrium will favour of the exothermic reaction – &
its yield is increased)
...
Pressure – only for gases (the side with a greater volume has more gas molecules – you can
count the gas molecules by the balancing numbers
...
If you lower the pressure, it favours the side with more
gas molecules/ more volume)
...
Concentration – this would stop dynamic equilibrium (if you increase the concentration of
reactants, the system tries to decrease it by producing more products
...


 The endothermic reaction causes a decrease in surrounding temperature; the exothermic reaction
causes an increase in surrounding temperature
...
(e
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gold, silver, copper, iron, zinc &
platinum)
...
Also, they have a high melting points (except mercury) & high densities
...

 Alloys are mixtures of a metal & either a metal or non-metal element
...

This is because different elements have different size atoms
...

 Shape memory alloys can return to their original shape after deformation
...

Different types of steel have different properties & uses, including: Low-carbon steel with 0
...
3%
carbon (which is easily shaped & used for car bodies), High-carbon steel with 0
...
5% carbon
(which is very strong, flexible, & brittle & used for cutting tool blades & bridges) & Stainless steel
with chromium or nickel sometimes added (which is corrosion-resistant & hard & used for cutlery
& corrosive substance containers)
...

 Brass is an example of a copper alloy
...
It is more
malleable than bronze & ideal with moving parts that require low friction (e
...
water taps & door
fittings)
...
It is harder & good for
making statues, decorative objects & medals
...
Pure gold is
described as 24 carat – the lower the carat, the lower the percentage of pure gold in the alloy
...

When it is mixed with magnesium, it makes the alloy Magnalium
...
If
the alloy has large amount of magnesium (50%), it is reactive & burns brightly like magnesium (but
it is more stable than magnesium), so it is used for fireworks
...
Rusting is specifically the corrosion of iron
(iron + oxygen + water –> hydrated iron (III) oxide)
...
Water with no air: iron nail in boiling tube with water & oil
...
Air with no water: iron nail in boiling tube with calcium chloride (drying agent)
...
CORROSION (air & water): iron nail with water & air
...
CONTROL (nothing): iron nail in Vaseline with calcium chloride
...


 Sometimes you must prevent corrosion to be safe, as structures become damaged over time
...
Painting or coating with plastic (can be decorative, has medium cost & is easy to put on, but it
will rust if scratched)
...
Oiling or greasing when moving parts are involved (has low cost & is easy to put on, but it is
easily removed)
...
Tin or chromium plating (has medium cost, is attractive & offers good protection, but rusts if
scratched & chromium is costly)
...
Electroplating using electrolysis to reduce metal ions onto iron electrode & coat it
...
Sacrificial protection – where a more reactive metal is placed with iron, so water & oxygen react
with that metal instead (e
...
galvanising – where zinc coat is sacrificed & acts as a barrier)
...

The cathode (negative electrode) is the object to be electroplated, & the anode (positive electrode) is
the metal that will coat the surface
...

 Electroplating has many uses, including: preventing corrosion & improving the appearance (e
...

cutlery & jewellery)
...


➢ QUANTITATIVE ANALYSIS
 Titrations is an experiment that tells you the exact volume of a reactant needed to react completely
with another reactant (e
...
neutralisation)
...

 HOW TO PERFORM A TITRATION:
1
...

2
...

3
...

4
...

5
...

6
...

7
...

8
...
Now do an accurate titration, take an initial reading, & run the acid within 2cm3 of the endpoint
...

10
...

11
...
1cm3 – this is known as concordant
...
Calculate mean volume concordant results of acid needed to neutralise alkali
...
It must have a sharp colour change (not
gradual), such as methyl orange or phenolphthalein
...

 CALCULATING CONCENTRATION:
concentration (mol/ dm3) = number of moles/ volume (dm3)

 HOW TO FIND CONCENTRATION OF AN UNKNOWN SOLUTION
...
Work out moles in known substance by rearranging formula (concentration x volume)
...
Write out balanced equation to work out molar ratios
...
Work out concentration of unknown substance (no
...

 CALCULATING CONVERSION FROM MOL / DM3 TO GRAMS/ DM3:
concentration (grams/ dm3) = concentration (mol/ dm3) x Mr
 The theoretical yield of a reaction is the amount you would get if all the reactants formed desired
products, & no products were lost
...
Finally, the percentage yield is a
comparison between the actual yield & theoretical yield
...

 HOW TO CALCULATE THEORETICAL YIELD:
1
...

2
...

3
...

4
...

 CALCULATING PERCENTAGE YIELD:
percentage yield = (actual yield/ theoretical yield) x 100
 Percentage yield are never 100% - although, in industry it is important to choose the reaction with
the highest percentage yield to reduce wastes & keep costs low
...

 Atom economy shows the percentage of mass of reactants that end up as desired products (useful,
not wasted)
...

 CALCULATING ATOM ECONOMY:
atom economy = (total Mr of desired products/ total Mr of all products) x 100
 Reactions with low atom economy use up resources quickly & produced a lot of waste that must be
disposed of
...
A solution is finding a use for the by-products (e
...
bitumen for
paving roads & roofs)
...
High percentage yield
2
...
High atom economy
4
...
Position of equilibrium (if reaction is reversible)
 Molar volume is the volume occupied by one mole of gas (measured in dm3/ mol)
...

 CALCULATING VOLUME OF GAS USING AVOGADRO’S LAW AT RTP:
volume of gas (dm3) = moles of gas x 24 dm3
 You can calculate the volume of gas from balanced equations using the molar ratio
...
This reaction is
reversible, so some ammonia reacts to form nitrogen & hydrogen again
...

 The following conditions are used for the Haber process: 450oC, 200atm & iron catalyst
...

 HOW THE HABER PROCESS WORKS:
1
...

2
...

3
...

4
...

5
...

 There are many factors to consider in industrial processes, including: cost & availability of raw
materials, rate of reaction (low temperatures slow it down), safety (high pressure increases risk of
explosion – & it is expensive), energy cost & supplies, & yield
...
The 450oC is a
compromise between maximum yield & rate of reaction
...
The high pressure increases both yield & rate of reaction
...

 The concentration of reactants is kept high to increase the yield of products (as the system tries to
make more products to decrease the reactants)
...
This also increases rate of reaction
...
You increase rate of
reaction by increasing temperature, pressure, & concentration of reactants as the molecules collide
more frequently & have the activation energy – hence, they increase the rate at which equilibrium is
reached
...

 Plants require nitrogen, phosphate, & potassium to growth – this is absorbed through the soil
...
Fertilisers replenish the elements to increase crop yield
...
They have advantages over manure,
such as the ability to control the composition of chemicals, how much is made, & its solubility (able
to dissolve in soil & get absorbed by plants)
...

 Solid fertiliser (ammonium salts) can be formed from reacting ammonia with acids – these are good
component for fertiliser as they have a high proportion of nitrogen per unit mass
...

ammonia + nitric acid –> ammonium nitrate















NH3(aq) + HNO3(aq) –> NH4NO3(aq)
Ammonium salts are also produced with sulfuric acid in the lab in batches (dilute sulfuric acid) or
continuously in industry
...
g
...
g
...

HOW TO PRODUCE AMMONIUM SULFATE IN THE LAB:
1
...
Then add methyl orange to flask
(turns yellow as it is an alkaline solution)
...
Slowly add dilute sulfuric acid (gently swirling each time) to ammonia solution until yellow turns
to red – this means it has been neutralised
...
As ammonium sulphate solution is not pure yet (with indicator), calculate the titre & repeat
without indicator
...
To get the solid crystals, gently evaporate solution with steam bath, when little is left, leave to
crystallise
...

In industry, the method above is too impractical for large quantities
...
One industrial method includes spraying sulfuric acid into a chamber of ammonia
gas to produce ammonium sulfate powder
...
A fuel cell is type of chemical cell that is
supplied with fuel (chemical energy) & oxygen/ air; it uses this reaction to efficiently release energy
– they can use different fuels & electrolytes
...
The reaction
between them produces a voltage & releases energy
...
g
...
There are no harmful pollutants produced, just
water
...
g
...

On the other hand, it also have disadvantages, including: hydrogen gas takes up a lot of space in
storage, hydrogen gas is explosive, requires fossil fuel to obtain hydrogen (either made from
hydrocarbons or by electrolysis of water – which requires electricity from fossil fuels), & expensive
to develop & install necessary technology for fuel cells (e
...
safe hydrogen tanks at petrol stations)
...

They are silvery but go dull when reacting with air, so they are stored in oil
...
They all have similar chemical properties as they have one
electron on their outer shell (e
...
highly reactive); they also have similar physical properties (e
...
low
melting/ boiling points, low density (can float) & soft enough to be cut with a knife)
...
As you go down the group,
the metals become more reactive (more readily lose electrons) since the outer electrons become
further from the nucleus – this is known as atomic radius
...

 Alkali metals can only form ionic compounds
...

 When alkali metals react with water, they form a metal hydroxide & hydrogen (general equation:
alkali metal + water –> metal hydroxide + hydrogen)
...
Since the metals become more reactive as
you go down the group, their reactions are more violent
...
Lithium: fizzes & moves around surface
...
Sodium: (fizzes & moves around surface) & melts
...
Potassium: (fizzes, moves around surface & melts) & ignites hydrogen to produce a flame
...
Rubidium & caesium: explode when they get wet
...
Goggles & a glass shield
should be used for safety
...
g
...

 Alkali metals burn rapidly in oxygen (alkali metal + oxygen –> metal oxide); they also burn
rapidly in chlorine (alkali metal + chlorine –> metal chloride)
...
They have seven
electrons on their outer shell, so they have similar chemical properties; these metals exist as diatomic
molecules (e
...
Br2) – sharing on pair of electrons in a covalent bond for a full outer shell
...

 HOW HALOGENS PHYSICAL PROPERTIES DIFFER (state at room temperature):
1
...
Bromine: red-brown liquid (poisonous & orange vapour)
...
Iodine: dark grey crystalline solid (poisonous & purple vapour)
 Group 7 metals gain a single electron (form 1- ions known as a halide ion)
...
Larger atomic radius means the electron is less strongly
attracted to the nucleus & more energy is required to attract it
...
Between
the colour change, the litmus paper may turn red as chlorine solution is acidic)
...
Hydrogen halides are soluble – when they










1
...




dissolve in water, they form acidic solutions (H+ & halogen-)
...
g
...

Displacement reactions between halogens cause the more reactive halogen to displace the less
reactive halogen from an aqueous solution
...
g 2Br- - 2e- –> Br2 or 2Br- –> Br2 + 2e-)
HOW TO DEMONSTRATE REACTIVITY TRENDS WITH DISPLACEMENT REACTIONS:
1
...

2
...

3
...
Otherwise, there was no reaction
...
Repeat process using different combinations of halogen & halide salt
...
From these results, chorine in the most reactive, then bromine, then
iodine
...
They have a full outer shell of electrons
(don’t need to lose or gain electrons to become stable)
...
At room temperature, they are colourless (& odourless) monatomic gases
...
g
...

Density: helium & neon are less dense than air, while xenon is heavier than air (e
...
helium is used
in airships & party balloons -low density allows it to float & non-flammability makes it safer than
hydrogen gas)
As you go down the group, the density & melting/ boiling point of the noble gases increase
...
You can find it by either measuring how quickly the
reactants are used up or how quickly the products are formed – which is easier
...

 CALCULATING MEAN RATE OF REACTION:
mean rate of reaction = quantity of reactant used or product formed/ time
 The units are dependent on the units used to measure the amount of product or reactant (either
units of amount of substance/ time or units of concentration of substance/ time)
...

Time is normally measured in seconds (or minutes)
...
Precipitation: recording the visual change if the initial solution is transparent & the product
clouds it by precipitating (becomes opaque)
...

2
...
Add reactants to conical flask with cotton wool (only
allows gas to escape) in the neck & measure how long it takes the mass to decrease to a constant
mass; you can plot a graph if you measure mass at regular time intervals – however, gas is being
releasing to the room (use fume cupboard)
...
Production of gas: measuring volume of gas given off using a gas syringe
...

 On graph of amount of product/ reactant over time, the rate of reaction is shown by the gradient
(steepness) of the line – steeper the line, the faster the rate of reaction
...
The reactions get slower with time because
the concentration of reactants decreases)
...
The fastest reaction would have
the steepest slope at the beginning & would flatten earlier; reactions that start with the same amount
of reactant flatten at the same level
...
To
calculate the rate of reaction at a section of the graph, you must work out the gradient; the units are
units of y-axis/ units of x-axis
...

 The rate at a particular point in a reaction curve can be found by drawing a tangent – which is a
straight line that touches the curve at a particular point without crossing it (done using a ruler &

straight line)
...
If the line
has a positive correlation, the value would be positive (& vice-versa)
...

 HOW TO INVESTIGATE THE EFFECT OF SURFACE AREA ON RATE (gas produced):
1
...

2
...

3
...

4
...

5
...

6
...

calcium carbonate + hydrochloric acid –> calcium chloride + carbon dioxide + water
CaCO3(s) + 2HCl(aq) –> CaCl2(aq) + CO2(g) + H2O(l)
 You could also measure mass lost
...

Therefore, the crushed (larger surface area) chips have the faster rate of reaction
...
Add excess hydrochloric acid to a conical flask
...
Add magnesium ribbon (after cleaning with emery paper) to solution & add gas syringe
...
Take reading of gas volume at regular time intervals until volume doesn’t change 3x
...
Put results in table & plot graph
...
Repeat experiment with different concentrations of hydrochloric acid
...

 Higher concentration gives faster rate of reaction
...
Measure 50cm3 of dilute sodium thiosulfate solution & 10cm3 of hydrochloric acid
...

2
...

3
...

4
...

Sodium thiosulfate + hydrochloric acid –> sodium chloride + sulfur dioxide + water
Na2S2O3(aq) + 2HCl(aq) –> 2NaCl(aq) + SO2(g)+ H2O(l)
 You should have the same person determine when the cross disappears, use fume cupboard as
sulfur dioxide is toxic, & both solutions are transparent, but they form a yellow precipitate (becomes
turbid/ cloudy)
...

 Collision theory explains reaction rates
...
Increasing
either of these increases the probability of successful collisions
...

 HOW COLLISION THEORY EXPLAINS INCREASED RATE OF REACTION:
1
...

2
...

3
...

4
...

 A catalyst is a substance that can speed up a reaction – without being chemically changed/ used up
or changing the reaction products
...
They speed up the reaction by provide a different
reaction pathway with a lower required activation energy; this allows more particles to have at least
the minimum amount of energy for the reaction to occur
...
They are often used in industry
(e
...
enzymes from yeast cells in the fermentation process of making alcoholic drinks – which
converts glucose into ethanol & carbon dioxide)
...
If the products store more energy than the
reactants, they have taken energy from the surroundings (if the store less, energy was transferred to
the surroundings)
...

 When energy is transferred to the surroundings, it is known as an exothermic reaction – it is shown
by a rise in temperature of the surroundings
...
Whereas, when energy is transferred from the surroundings, it is
known as an endothermic reaction – it is shown by a fall in temperature of the surroundings
...

 Reversible reactions are exothermic in one direction & endothermic in the other- however, the same
amount of energy is transferred (e
...
hydrated copper sulfate ⇌ anhydrous copper sulfate +
water (CuSO4
...

 Reaction profiles/ energy level diagrams show how the amount of energy in a reaction changes as it
progresses
...
The graph
starts at the reactants’ energy levels & finishes with the products’ energy level – they are connected
by a smooth curve
...
Overall energy/ enthalpy change measured in ΔH: difference between energy of reactants &
products by difference in height
...
Whether reaction in exothermic or endothermic: they show the relative energies of the reactants
& products
...
















3
...

You can find it form the difference between the start of the curve & the highest point
...
Presence of a catalyst: catalyst provide a different reaction pathway with a lower required
activation energy; this is drawn on a reaction profile as a shorter curve under a larger one
...

HOW TO MEASURE TEMPERATURE CHANGE:
1
...

2
...

3
...

4
...
Record maximum or minimum temperature reached during reaction
...
Calculate temperature change
...

Energy is measure in joules (J) or kilojoules (KJ)
...

Energy must be supplied when bonds are broken, so it is an endothermic process; energy is released
when bonds are formed, so it is an exothermic process
...

Bond energy calculations show how much energy is required to break a certain chemical bond
(stronger the bond, more energy needed to break it)
...
Draw out displayed formula of molecules in the reaction (shows those made & broken)
...
Work out energy used in bond breaking by adding bond energies of all bonds in the reactants
...
Work out energy used in bond forming by adding bond energies of all bonds in the products
...
Calculate energy change overall
...


TOPIC 8: Fuels & Earth Science
 Crude oil is a complex mixture of many different hydrocarbons – which are compounds containing
only hydrogen & carbon
...
Natural gases are a mixture of gases that form underground the same way
...
Most hydrocarbons in crude oil
alkanes (general formula: CnH2n+2); the carbon atoms in the molecules are arranged as chains or
rings
...
The fractions contain groups of hydrocarbons with
similar lengths (small number of hydrogen & carbon atoms)
...
Crude oil is pumped into a fractional column – which has a temperature gradient (hottest at the
bottom)
...
Crude oil is heated so that most of it evaporates, & it can be piped in the bottom of the column
(here the liquid part called bitumen is drained off)
...
Gas rises up the column & gradually cools
...
Different compounds in the mixture have different boiling points, so they condense at different
temperatures – which are at different levels in the fractional column
...

 HOW CRUDE OIL FRACTIONS ARE USED (from lowest boiling point/ top of column):
1
...

2
...

3
...

4
...
g
...

5
...

6
...

 As the boiling point lowers, other factors change as well, including: smaller molecules, lower
viscosity/ thickness, high volatility (ease of evaporation), & higher flammability
...
Hydrocarbons with similar
chemical properties can be grouped in a homologous series – which is a family of molecules with
the same general formula & share similar chemical properties; the molecular formulae of
neighbouring compounds in a homologous series differ by a CH2 unit
...
g
...
This is evident in the fractions of crude oil as
they are mostly part of the alkane homologous series
...
Each fraction
contains hydrocarbons with similar numbers of carbon atoms, so the molecules have similar
chemical properties & behave similarly
...


 HOW PHYSICAL PROPERTIES OF HYDROCARBONS DIFFER:
1
...

2
...
The gas molecules mix with oxygen in
the air – this gas mixture ignites if it comes in contact with a spark
...
Viscosity/ thickness (how easily a substance flows): stronger the intermolecular forces are,
harder it is to flow; longer chain hydrocarbons have higher viscosity
...
Energy is released to the surroundings – making it an exothermic reaction
...

 However, if the reaction has insufficient oxygen in the air, they undergo incomplete combustion
(this happens in some appliances, like boiler that use carbon compounds as fuel)
...

 Carbon monoxide can bind to the haemoglobin in red blood cells – which normally carries oxygen;
this means less oxygen can be transported around your body; a lack of oxygen in the blood supply
can lead to fainting, coma, or death
...
If a household appliance is
producing carbon monoxide or soot, it is inefficient & a serious health hazard
...
When sulfur
dioxide mixes with water in clouds, they react to form dilute sulfuric acid – which falls as acid rain
...

 When fuels are burnt in the internal combustion engines of a car, they release a lot of energy in the
form of heat; these high temperatures cause the nitrogen & oxide in the air to react & form nitrogen
oxides (reverted back using catalytic converters)
...

 Instead of using petrol to power vehicles, hydrogen can be used; it can also be used for fuel cells
...
Advantages: fuel cell produce energy with waste product of water, no harmful pollutants
released, obtaining from water (renewable resource), & can be obtained from waste product of
fuel cell
...
Disadvantages: special, expensive energy required to use hydrogen as a fuel, must be
manufactured – which is expensive & requires energy from fossil fuels releasing pollutants
(normally) for electrolysis of water, highly flammable, hard to store safely, & expensive as it is
not widely available
...
It produces
alkanes (saturated) & alkenes (unsaturated)
...
The hydrocarbon is vaporised & passed over a powdered catalyst (e
...

aluminium oxide); pressure of 70 atm & high temperature of 400-700oC are used to break the strong
covalent bonds
...

 Earth’s surface was originally molten for millions of years; it was so hot that any atmosphere
dispersed into space
...

These gases formed early atmosphere of mostly carbon dioxide (no oxygen); other gases released
include nitrogen, water vapour, methane (CH4) & ammonia (NH3)
...

 Although the early atmosphere was mostly carbon dioxide, it has gradually decreased over time
...
Absorption by oceans: carbon dioxide dissolved into the oceans; after a series of reactions, it
formed carbonate precipitates that formed sediments on the seabed
...
g
...

2
...
They absorbed
carbon dioxide from the atmosphere & used it for photosynthesis
...
The increase of oxygen levels allowed more complex life (e
...
animals) that used
oxygen
...
Finally, it reacted with ammonia to produce nitrogen
...

 The levels of oxygen increased, & the levels of carbon dioxide decreased over time to the produce
the current composition of gases in the atmosphere
 You can test for the presence of oxygen by placing a glowing splint inside a test tube; if oxygen is
present, the splint will relight
...

 HOW THE GREENHOUSE EFFECT WORKS:
1
...

2
...

3
...

4
...

5
...

 Human activities are thought to have caused a rise in greenhouse gas concentration in the
atmosphere
...
Increased levels of greenhouse gases increase the greenhouse effect, so more
infrared radiation is absorbed & radiated towards earth causing it to warm – this is known as global
warming
...
Over the last 150
years, the world population has rapidly increased (more energy needed for lighting, heating, cooking
& transport) & we have become more industrialised (lifestyles changed to become more electrical &













vehicular); this means we’ve increased our energy consumption & we’re burning more fossil fuels –
which released the carbon dioxide ‘locked’ inside
...
This is a problem because plants absorb carbon dioxide when they photosynthesise (less
being removed)
...
As
population increases, more food must be produced, & more methane is produced
...

Historically, temperature change at earth’s surface is correlated to the concentration of carbon
dioxide in the atmosphere; recently, both have increased
...

HOW CLIMATE CHANGE HAS NEGATIVE EFFECTS:
1
...

2
...

3
...

4
...

Historical data is less accurate since it was taken in fewer location & the equipment has lower
resolution
...
There are ways to estimate past data,
including: fossil analysis, tree rings or carbon dioxide gas bubbles in ice sheets
...

HOW TO MITIGATE/ LESSEN THE EFFECTS OF CLIMATE CHANGE:
1
...
g
...

2
...

3
...

4
...


TOPIC 9: Separate Chemistry 2
➢ TESTS FOR IONS
 Ionic compounds are made up of anions & cations; there are specific tests you can perform to
identify which ions are in a compound
...

 HOW TO IDENTIFY USING FLAME TESTS:
1
...

2
...

3
...

4
...

5
...

 Before placing in the flame, you must first clean the nichrome wire loop by dipping it in
hydrochloric acid (& rinsing it in distilled water)
...

 Many metal hydroxides are insoluble, so they precipitate out of solution – some of which have
characteristic colours; you can test some metal ions by adding a few drops of sodium hydroxide
(NaOH) solution (aqueous) to a solution (aqueous) of the metal ion to form solid precipitates
...
Calcium (Ca2+) = white precipitate (ionic equation: Ca2+ + 2OH- –> Ca (OH)2)
...
Copper (II) (Cu2+) = blue precipitate (ionic equation: Cu2+ + 2OH- –> Cu (OH)2)
...
Iron (II) (Fe2+) = green precipitate (ionic equation: Fe2+ + 2OH- –> Fe (OH)2)
...
Iron (III) (Fe3+) = brown precipitate (ionic equation: Fe2+ + 2OH- –> Fe (OH)3)
...
Aluminium (Al3+) = white precipitate (ionic equation: Al2+ + 2OH- –> Al (OH)3)
...

 To work out whether a substance contains ammonium ions (NH4+), you must add sodium
hydroxide solution to the solution you’re testing & gently heat it
...

 You can test for carbonate ions (CO32-) using the reaction: carbonate + acid –> salt + carbon
dioxide + water; when you add the acid, the mixture fizzes & gives off carbon dioxide gas
...

 You can test for halide ions (Chloride, bromide, or iodide) by adding dilute nitric acid (HNO3) then
adding silver nitrate solution (AgNO3)
...
Chloride (Cl-) = white precipitate (ionic equation: Ag+ + Cl- –> AgCl)
...
Bromide (Br-) = cream precipitate (ionic equation: Ag+ + Br- –> AgBr)
...
Iodine (I-) = yellow precipitate (ionic equation: Ag+ + I- –> AgI)
...


 You can test for sulfate ions (SO42-) by adding dilute hydrochloric acid, then adding barium
chloride
...

The hydrochloric acid is used to remove any carbonate ions – which also would form a white
precipitate
...

 HOW FLAME PHOTOMETRY WORKS:
1
...

2
...

3
...

4
...

 Since every ion has a different charge & electron arrangement, they all emit different wavelengths of
light; this means each ion produces a different pattern of wavelengths & has a different line
spectrum
...
You can work out of the concentration using the emission intensity on a calibration
curve (straight or curved graph that always goes through the origin); the x-axis is labelled
concentration of ion & the y-axis is labelled emission intensity
...
Sensitivity: able to detect the smallest of concentrations
...
Speed: tests can be automated to speed up process
...
Accuracy: don’t involve human error (quantitative data)
...
Ability to identify mixtures
...
Each carbon atom forms four bonds
& the hydrogen atoms form one bond; this means all the atoms have formed as many covalent
bonds as they can – this is known as saturated
...

 Alkenes are more reactive than alkanes as they contain the functional group C=C (double covalent
bond between two of the carbon atoms in their chain)
...

 They have a general formula for CnH2n; it starts with ethene (C2H4), propene, then butene
...

 All alkenes react with bromine in an addition reaction; the double bonds open up -which leaves a
single bond- & each carbon atom involved forms a single bond with a bromine atom
...

 This is drawn by replacing the double bond with a single bond & adding a bromine atom to each
...


 Alkenes can make polymers by addition polymerisation – where small alkene molecules (monomers)
open their double bonds & join together to form long-chain molecules (polymers)
...

 HOW TO DRAW STRUCTURE OF AN ADDITION POLYMER:
1
...

2
...

3
...

 Polymers have a high relative formula mass
...
Poly (ethene): flexible, electrical insulator & cheap (used for plastic bags, bottle, & wire
insulation)
...
Poly (propene): flexible, strong, tough, & mouldable (used for crates, furniture, & ropes)
...
Poly(chloroethene)/PVC: tough & cheap (used for window frames & water pipes)
...
Poly (tetrafluoroethene): unreactive, tough, & non-stick (used for non-stick pans & waterproof
clothing)
...
Each time a new bond is formed, a small
molecule is lost (e
...
water or hydrochloric acid)
...
The molecule with the ester link has a functional group at each end; these functional groups
can react in more condensation polymerisation to form a longer chain
...
Draw a dicarboxylic acid + a diol (as a box or ‘R’– which represents a carbon chain) with the
functional group on each side of it), then add an arrow
...
Next remove the water molecule (H2O) from both functional groups (forms the ester link)
...
Connect the remaining monomers together
...
Draw brackets around the monomer, add lines on either side & put an ‘n’ in the corner
...
Finally, add a water molecule with ‘n’ (nH2O)
...

 Raw material of polymers is crude oil – which is a finite resource & while eventually be used up
...

 HOW TO DISPOSE OF POLYMERS:
1
...

2
...

3
...


➢ ALCOHOLS & CARBOXYLIC ACIDS
 Alcohols are a homologous series containing the -OH functional group
...
It begins with methanol (CH3OH), ethanol, propanol,
then butanol
...

 It can be represented as a molecular formula (ratio of atoms), structural formula (shows functional
group), or displayed formula (2D representation of covalent bonds)
...

 When you heat a mixture an alcohol with an acid catalyst, an alkene & water are formed – this is
known as a dehydration reaction
...
g
...
The carbohydrates
mostly come from sugar cane or beet plants; the yeast cells contain enzymes (zymase) – which speed
up the reaction
...
Mix yeast & carbohydrate solution, seal container & leave in warm place
...
Keep at optimum temperature of 30-40oC for enzymes (too low, too slow; too high causes it to
denature & stop reaction); keep anaerobic conditions (or ethanol becomes ethanoic acid when
oxidised & aerobic respiration to produce water, instead of ethanol)
...
When concentration reaches 10-20%, fermentation reaction stops – this is because the alcohol
kills off the yeast
...
Collect ethanol solution from the top since the yeast will fall to the bottom
...
g
...
g
...

 To increase the concentration, fractional distillation is used; this is because ethanol has a lower
boiling point at 78oC compared to water at 100oC
...

 It is best to use an electric heater as ethanol is flammable
...
The amount of energy is gives out determines how good of a fuel it is (more is better)
...
Put some alcohol into a spirit burner, then measure the mass of the burner & fuel on a mass
balance
...
Measure 100 cm3 of distilled water into a copper calorimeter
...
Insulate the calorimeter with a draught excluder & cover with insulating lid – then add a
thermometer
...
Take the initial temperature of the water, then put the burner under the calorimeter & light
...
Continue to stir water using the thermometer (blow out burner when temperature reaches 20oC)
...
Find mass of fuel that has been used (subtract final mass from initial)
...
Repeat with different alcohols
...


 Carboxylic acids are a homologous series containing the functional group -COOH; this means they
have a carbon atom that has a double bond with an oxygen as well as a single bond with an -OH
group
...

 They are weak acids; this is because they only partially ionise to release H+ ions in solution
...

 Carboxylic acids are produced when an alcohol is oxidised (gains oxygen)
...
A nanoparticle
has a diameter between 1nm and 100nm; they contain a few hundred atoms – which are studied in
nanoscience
...
Bulk materials have a smaller surface area:
volume ratio, so nanoparticles have a larger proportion of their atoms available to interact with
substances they encounter; this means that they have different properties
...
Catalysts: faster rate of reaction as the surface area is large (more collisions) – an example is
platinum in fuel cells (it is expensive but only few are needed)
...
Nanomedicine: absorbed easier into the body and can be used to deliver drugs to exact location
(e
...
fullerenes)
...
Electronics: some can conduct electricity (e
...
thin, light display screens or tiny memory chips)
...
Sunscreens: better to protect from harmful UV rays, give better coverage and no white marks
...
Deodorants: silver nanoparticles have antibacterial properties
...
Cosmetics: (e
...
deliver ingredient to lower layers of skin)
...
Sports equipment: added to materials to make them stronger and more durable (e
...
golf balls)
...

 Polymers are large molecules formed when smaller molecules (monomers) join by covalent bonding
...
However, they can degrade over time
...
g
...
They are great
heat and electricity insulators, strong, hardwearing and don’t degrade or corrode
...

 HOW CERAMICS DIFFER:
1
...
It is soft when
dug out and can be moulded, but at high temperatures, it hardens into clay ceramic; hence, it is
ideal for pottery and bricks
...
Glass: normally from heating a mixture of limestone, sand, and sodium carbonate (soda) to form
soda-lime glass when it melts
...

 Composites are made of one material embedded in another; fibres/ fragments of a material called
the reinforcement are surrounded by a matrix/ binder; these determine the properties (e
...
fibreglass
– fibres of glass in polymer matrix, carbon fibre – carbon fibres/ nanotubes in polymer matrix, or
concrete – aggregate of sand and gravel in cement matrix)
...


 Metals are good conductors of heat and electricity, malleable, and less brittle
...
They can be mixed to
form alloys (e
...
steel)

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