Oxford Revise AQA GCSE Chemistry

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

Niels Bohr—electrons orbit the nucleus at

James Chadwick—the nucleus contains neutrons

1

1

AO1

4.1.1.3

01.2

any six from:

• alpha particles/helium nucleus fired at gold foil
• Most passed through the gold foil
• So most of the atom is empty space
• a small number bounced back
• so must have collided with something/mass/nucleus
• a small number passed through but were deflected/changed direction
• positively-charged alpha particles passed near positively charged nucleus and were repelled

6

AO1

4.1.1.3

01.3

19

1

AO2

4.1.1.4

02.1

fractional distillation

do not accept distillation or simple distillation

1

AO2

4.1.1.2

02.2

mixture is heated

both liquids will give off vapours before their boiling point

vapours enter fractionating column (with glass beads)

water will condense on glass beads as it has a higher boiling point (than isopropanol)

isopropanol will continue to rise and pass into condenser

will then condense and can be collected in separate vessel

1

1

1

1

1

1

AO1

4.1.1.2

02.3

boiling point too similar

1

AO2

4.1.1.2

03.1

similarities:

• both suggest that atoms are spherical
• both suggest different elements have different atoms of different masses

differences:

• earlier model states that atoms cannot be divided
• plum pudding suggests that negative electrons are embedded in a ball of positive charge

award 1 mark per point

3

AO1

4.1.1.3

03.2

Level 3: A detailed and coherent explanation is given. All three observations of the experimental evidence are explained.

5–6

AO1

4.1.1.3

Level 2: A coherent explanation is given, but not all observations are linked to aspects of the model.

3–4

Level 1: Some correct points are made. At least tone observation is given and linked to aspects of the model.

1–2

No relevant content

0

Indicative content

• positively-charged alpha particles fired at gold foil
• most alpha particles travelled straight through the foil
• suggesting most of the atom is empty space
• a small number of alpha particles bounced back
• suggesting mass of the atom was concentrated in the centre of the atom
• a small number of alpha particles were deflected
• suggested the central mass had positive charge
• the positively-charged nucleus repelled positive alpha particles, causing the deflection

allow answer in terms of plum pudding model, for example, alpha particles would not have passed through if plum pudding model is correct etc.

04.1

16

1

AO2

4.1.1.4

04.2

17

1

AO2

4.1.1.4

04.3

Y

1

AO3

4.1.1.5

04.4

X and Z

both required for the mark

1

AO3

4.1.1.5

05.1

17

accept same number of electrons

1

AO1

4.1.1.4

05.2

17

1

AO1

4.1.1.4

05.3

chlorine has (two) isotopes with different abundance

relative atomic mass is an average

students do not need to list the isotopes of chlorine to gain mark

accept calculation for 2 marks

1

1

AO1

4.1.1.5

05.4

1

1

1

AO2

4.1.1.6

05.5

other isotopes of copper exist

1

AO3

4.1.1.6

06.1

number of protons = number of electrons = 11

mass number = number of protons + number of neutrons

= 11 + 12 = 23

1

1

AO2×1

AO3×1

4.1.1.5

06.2

in both atoms, the electrons are arranged in shells/energy levels

in both atoms, there are three shells/energy levels

in both atoms, the shell/energy level nearest the nucleus has two electrons/is full

in both atoms, the shell/energy level second from the nucleus has eight electrons/is full

in sodium, the outer shell/energy level has one electron only and is not full

in argon, the outer shell/energy level has eight electrons and is full

1

1

1

1

1

1

AO2

4.1.1.7

06.3

1

1

AO2

4.1.1.5

07.1

mass numbers:

L = 14 + 14 = 28 M = 14 + 15 = 29 N = 14 + 16 = 30

percentage abundance of N = 100 – (92.2 + 4.68) = 3.12%

relative atomic mass =
\(
\begin{array}{l}
\frac{{(92.20 \times 28) + (4.68 \times 29) + (3.12 \times 30)}}{{100}}\\
= 28.1092\\
= 28.1
\end{array}
\)

1

1

1

1

1

AO1×2

AO2×3

4.1.1.6

07.2

three shells

two electrons in first shell, eight electrons in second shell, and four electrons in third shell

accept one shell shown with four electrons for 1 mark

1

1

AO1

4.1.1.7

07.3

both isotopes will have the same chemical properties

as they have the same number of (outer) electrons

1

1

AO1

4.1.1.5

08.1

−1

any units given negate mark

1

AO1

4.1.1.4

08.2

two crosses in shell nearest centre

eight crosses in next shell

four crosses in outer shell

accept dots for electrons

all electrons must be drawn with the same shape

1

AO2

4.1.1.7

08.3

(Niels) Bohr

1

AO1

4.1.1.3

09.1

atoms of the same element/with the same atomic number/same number of protons but a different number of neutrons

1

AO1

4.1.1.5

09.2

The three isotopes have the same atomic number.

1

AO1

4.1.1.5

09.3

1

1

1

AO2

4.1.1.6

10.1

zirconium

1

AO2

4.1.1.4

10.2

calcium

1

AO2

4.1.1.5

10.3

2.8.8.2

accept 2,8,8,2

1

AO2

4.1.1.7

10.4

10.5

award 1 mark for every two points plotted correctly

award 1 mark for correct line of best fit

3

1

AO2×3

AO3×1

4.1.1.5

10.6

as the number of protons increases, so does the number of neutrons

not directly proportional (as the number of protons increases, the number of neutrons increases more quickly)

accept not linear/ non-linear

1

1

AO3

4.1.1.5

11.1

triangle

accept drawn symbol

do not accept water

1

AO2

4.1.1.1

11.2

A

1

AO2

4.1.1.1

11.3

C

1

AO2

4.1.1.1

4.1.1.2

11.4

D

1

AO2

4.1.1.1

4.1.1.2

11.5

NaCl

must have capitalisation shown

accept ClNa

1

AO2

4.1.1.1

12.1

silicon atoms have more electron shells

1

AO3

4.1.1.7

12.2

1.22×10⁻¹⁰ (m)

1

AO2

4.1.1.5

12.3

1

1

1

AO2

4.1.1.5

12.4

accept answer gained from converting metres to nm

1

1

AO1×1

AO2×1

4.1.1.5

13.1

filtration

1

AO1

4.1.1.2

13.2

Level 3: A full description of the method provided, with at least two pieces of equipment named.

5–6

AO1

4.1.1.2

Level 2: Basic method provided, identifying that the water needs to evaporate (either by heating or by being left). At least one piece of equipment identified.

3–4

Level 1: Method identifies idea that water needs to evaporate/be heated. No equipment named.

1–2

No relevant content

0

Indicative content

• mixture placed in evaporating dish
• evaporating dish placed on beaker half full of water
• place beaker/evaporating dish on tripod and gauze
• heat the mixture/water
• using Bunsen burner
• until crystals start to form
• remove mixture from the heat
• leave for the rest of the water to evaporate

13.3

chromatography

1

AO1

4.1.1.2

14.1

A

1

AO2

4.1.1.2

14.2

dyes B and C produced spots that overlap with dye A and each other

therefore cannot distinguish whether dye B or C produces the top spot

1

1

AO3

4.1.1.2

14.3

rerun experiment with difference mobile phase/solvent

1

AO3

4.1.1.2

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

high melting point—strong covalent bonds

does not conduct electricity—there are no charged particles free to move

1

1

AO1

4.2.2.6

01.2

C

1

AO1

4.2.2.6

01.3

oxygen: small molecule/simple molecular

silicon: giant covalent structure

1

1

AO2

4.2.2.6

4.1.1.3

02.1

phosphorous: five dots/crosses in total, three should be inside the overlap between the phosphorous and hydrogen molecules

hydrogen: three crosses/dots (one per hydrogen), which should be in the overlap between the phosphorous and hydrogen molecules

2

AO2

4.2.1.4

02.2

intermolecular

1

AO1

4.2.2.4

02.3

gas

1

AO1

4.2.2.1

02.4

as radius of central atom increases, boiling point increases

because strength of intermolecular forces increases with increasing size of molecule/because there are more electrons

1

1

AO2

4.2.2.4

03.1

there are no gaps/sticks between the atoms

1

AO1

4.2.1.4

03.2

some of its electrons are free to move

1

AO1

4.2.3.2

03.3

\(\frac{0.24}{{1.99 \times {{10}^{23}}}}\)
\(=1.206 \times {10^{-24}}\)
\(=1.21 \times {10^{-24}}\)

1

1

1

AO2

04

Level 3: A detailed and coherent explanation is given, demonstrating a sound knowledge of the differences in properties and the reasons for them.

5–6

AO1

4.2.3.1

4.2.3.2

Level 2: A correct description is given of the properties of each allotrope. Some reasons are given, but are not clearly articulated/not clearly linked to the property.

3–4

Level 1: Some correct points are made about each structure. Comparisons and reasons are not included.

1–2

No relevant content

0

Indicative content

• graphite conducts electricity, but diamond does not
• because graphite includes delocalised electrons, but diamond does not
• graphite is soft, but diamond is hard
• because the layers in the structure of graphite can slide over each other, but there are no such layers in diamond/diamond has lots of strong bonds
• both have high melting and boiling points
• because both include strong covalent bonds between their atoms

05.1

Z

1

AO2

4.2.3.2

05.2

each chlorine should have seven dots/crosses, with one electron shared from each (one pair shared in total)

allow only one mark if both chlorines have dots or crosses

2

AO2

4.2.1.4

05.3

each oxygen should have six dots/crosses, with two electrons shared from each (two pairs shared in total)

allow 1 mark if only one shared pair of electrons (single bond), but a total of 8 electrons around each atom

2

AO2

4.2.1.4

05.4

Y

chlorine has a higher melting point because it has more electrons/stronger intermolecular forces

1

1

AO3

4.2.2.4

06.1

low melting point

because compound X consists of small molecules

does not conduct electricity

because compound X does not include charged particles that are free to move

accept soluble in water with correct explanation of hydrogen bonding.

ignore the name of the compound/ethanol

1

1

1

1

AO1×2

AO2×2

4.2.2.4

06.2

C₂H₅OH/C₂H₆O

1

AO1

4.1.1.4

06.3

\({\rm{there\ are\ }}6{\rm{\ hydrogen\ atoms}}:\)
\(6 \times 6.02 \times {10^{23}} = \;3.61 \times {10^{24}}{\rm{\ atoms}}\)

1

AO2

06.4

liquid

1

AO2

4.2.2.1

07.1

Z

1

AO3

4.2.3.3

07.2

high (tensile) strength

1

AO1

4.2.2.3

07.3

electronics, because nanotubes conduct electricity

reinforcing composite materials, because nanotubes have high tensile strength.

both the use and the reason are required for each mark

1

1

AO1

4.2.2.3

08.1

C₆H₁₄

1

AO2

4.2.1.4

08.2

carbon: four dots/crosses in total, one should be in the overlap of each hydrogen

hydrogen: four molecules with one electron each (shown as a cross/dot), each electron should be within the overlap of carbon and hydrogen

one mark for carbon

one mark for hydrogen

2

AO1

4.2.1.4

08.3

one carbon with 4 hydrogens surrounding it, which are each joined to the carbon by one stick

1

AO1

4.2.1.4

08.4

Level 3: A detailed and coherent comparison is given, demonstrating a sound understanding of the properties of liquids and gases.

5–6

AO1×4

AO3×2

4.2.2.1

Level 2: Correct comparisons are made, showing some understanding of the properties of liquids and gases. The answer is not clearly articulated.

3–4

Level 1: Some correct points are made about the properties of liquids and/or gases.

1–2

No relevant content

0

Indicative content

• methane is a gas at room temperature
• but hexane is in the liquid state
• both substances can be poured/both substances have no fixed shape/both substances take the shape of the bottom of their containers
• hexane has a greater density than methane (at room temperature)
• because both include strong covalent bonds between their atoms

08.5

hexane has stronger forces between its particles than methane

so more energy is required to separate the particles in hexane than in methane

1

1

AO2

4.2.2.1

09.1

Level 3: A detailed and coherent answer is given.

5–6

AO2×3

AO3×3

4.2.2.4

Level 2: The explanation is correct, but the answer is not clearly articulated.

3–4

Level 1: Some correct points are made, but the answer is not clearly articulated.

1–2

No relevant content

0

Indicative content

• fluoroethene, chloroethene and bromoethane are compared since they only differ by one atom
• number of electron energy levels/shells increases from fluorine to chlorine to bromine
• boiling point increases from fluoroethene to chloroethene to bromoethene
• indicating that the strength of intermolecular force also increases from fluoroethene to chloroethene to bromoethane

09.2

fluoroethene

1

AO3

4.2.2.5

09.3

this should match figure 5, but only a single bond joins the two carbons

this polymer should be enclosed in brackets, with the extra bond from each carbon extending out of the brackets (as in figure 4)

there should be a subscript n after the brackets

1

AO2

4.2.2.5

09.4

bromoethene is a gas at room temperature

so it has no fixed shape/can be poured/ takes the volume of its container

poly(bromoethene) is solid at room temperature (because it is a polymer)

so it has a fixed shape/cannot be poured/ has a fixed volume

1

1

1

1

AO2

4.2.2.1

10.1

carbon with four electrons, sharing two electrons with each oxygen

each oxygen has six electrons, sharing two electrons with each carbon

allow 1 mark if only one shared pair of electrons (single bond), but a total of 8 electrons around each atom

2

AO2

4.2.1.4

10.2

silicon dioxide, SiO₂, has a higher boiling point/carbon dioxide, CO₂, has a lower sublimation point

boiling silicon dioxide involve breaking strong covalent bonds

subliming carbon dioxide involves breaking weak intermolecular forces

1

1

1

AO1

4.2.2.4

4.2.2.6

11.1

bond strengths decrease as number of electron energy levels/shells increase as you go down the group

because the bonding electrons are less attracted to the nucleus

1

1

AO3

4.2.2.4

11.2

N₂ – five electrons per outer shell, three electrons shared per nitrogen (three pairs shared in total)

O₂ – six electrons per outer shell, two electrons shared per oxygen (two pairs shared in total)

H₂ – one electron per outer shell, one electron shared per shell (one pair shared in total)

Triple bonds are stronger than double bonds and double bonds are stronger than single bonds.

1

1

1

1

AO2

4.2.1.4

12.1

\({\rm{mass}} = 7 \times 1.7 \times {10^{-27}}{\rm{kg}} = 1.19 \times {10^{-26}}{\rm{kg}}\)
\({\rm{volume\ }} = \frac{4}{3}\;{\rm{\pi\ }} \times {\left( {1 \times {{10}^{-14}}} \right)^3} = 4.19 \times {10^{-42}}{{\rm{m}}^3}\)
\({\rm{density}} = \frac{{{\rm{mass}}}}{{{\rm{volume}}}}\)
\({\rm{density}} = \frac{{1.19 \times {{10}^{–26}}}}{{4.19 \times {{10}^{–42}}}} = 3 \times {10^{15}}{\rm{kg/}}{{\rm{m}}^3}{\rm{to\ }}1{\rm{\ significant\ figure}}\)

1

1

1

1

AO2

12.2

All matter is spread evenly throughout nucleus.

1

AO3

12.3

no

because the mass of the atom is concentrated in the nucleus/the density of the atom is not the same throughout the atom

accept an explanation that relates to 13.2 if the assumption given in 13.2 was valid.

1

1

AO3

12.4

assumes that there are no forces between the spheres

forces between the particles affect the physical properties of the substance

OR

assumes that spheres are solid

most of an atom is empty space with a solid nucleus

OR

assumes atoms do not contain subatomic particles/atoms do contain electrons, neutrons and protons/atoms do contain subatomic particles

2

AO1

4.2.2.1

13.1

1

AO2

4.1.1.5

13.2

\({\rm{E}}\)
\({}_7^{15}{\rm{N}}\)

1

1

AO2

13.3

\({\rm{D}}\)
\({}_{12}^{24}{\rm{M}}{{\rm{g}}^{2+}}\)

1

1

AO2

4.1.1.5

13.4

\({\rm{Mg\ or}}{}_{12}^{25}{\rm{Mg}}\)
\({\rm{mass\ }} = 25\)
\({\rm{atomic\ number\ }} = 12\)

1

1

AO2

4.1.1.5

14

Level 3: A detailed and coherent answer is given. All equipment is correctly identified.

5–6

AO1

AO3

4.1.1.2

Level 2: An explanation is given with two or three pieces of equipment correctly identified.

3–4

Level 1: An explanation is given, but it lacks structure. Only some equipment is named.

1–2

No relevant content

0

Indicative content

• filter paper is placed into funnel
• funnel is placed into a conical flask/beaker
• pour reaction mixture into filter paper
• solution will collect in the conical flask/beaker
• magnesium will collect in the filter paper
• wear safety glasses when working with acid

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

they conduct electricity in the solid and liquid states

1

AO1

4.2.2.8

01.2

giant structure

ions arrange in regular pattern

electrons in outer shells/outermost electrons delocalised

reject ‘atoms’

1

1

1

AO1

4.2.1.5

01.3

atoms/ions are arranged in layers

that can slide over each other

do not penalise ‘atoms’ again here

1

1

AO1

4.2.2.7

01.4

most metals have high melting points/most metals are solid at room temperature

1

AO1

4.2.2.7

02.1

the ions/particles are arranged in layers

that can slide over each other

do not penalise ‘atoms’ again here

1

1

AO1

4.2.2.7

02.2

strong metallic bonding

because shared delocalised electrons can move through the whole structure

large amounts of energy are needed to overcome the strong metallic bonding

1

1

1

AO1

4.2.2.7

02.3

less likely to be damaged by scratching (since harder)

1

AO2

4.2.2.4

02.4

other atoms have a different size to platinum atoms

so the layers of atoms are distorted

so they cannot slide over each other so easily

1

1

1

AO1

4.2.2.7

03.1

350

allow between 352-358

1

AO2

4.2.2.3

Maths

03.2

A

1

AO2

4.2.2.7

03.3

B

1

AO2

4.2.2.3

03.4

A: ethanal, C: hexanol

hexanol is a larger molecule than ethanol

so hexanol will have a higher boiling point

1

1

1

AO3

4.2.2.4

04.1

each circle has 2+ charge

16 minus charges/electrons/e^– around the circles

for one mark, accept a ‘+’ charge put in every circle and any number of ‘-’ charges put around the circle.

1

1

AO1

4.2.1.5

04.2

Mg ion should have one ring with 8 dots. This should be inside square brackets with an uppercase 2+ outside the brackets.

O ion should have one ring with 2 dots and 6 crosses. This should be inside square brackets with an uppercase 2-outside the brackets.

one mark for correct magnesium ion

one mark for correct oxygen ion

1

1

AO2

4.2.1.2

04.3

magnesium oxide – conducts electricity in the liquid state only because its ions are then free to move

magnesium – conducts electricity in the solid and liquid states because its delocalised electrons are free to move

1

1

AO1 × 2

4.2.2.3

4.2.2.8

04.4

2Mg(s) + O₂(g) → 2MgO(s)

3

AO2

4.1.1.1

4.2.2.2

04.5

alloy is harder than pure metal

so will be more durable/last longer

1

1

AO1 × 1

AO2 × 1

4.2.2.3

4.2.2.8

05.1

metal ions arranged in a regular structure

surrounded by delocalised electrons from outer shells.

1

1

AO1

4.2.1.5

05.2

Level 3: A detailed and coherent answer is given, including points that support and do not support the statement that are clearly linked to the data in the table. A conclusion is provided and justified using the data.

5-6

AO2 × 2

AO3 × 4

4.2.2.8

Level 2: Points that support and do not support the statement are made, but these are not always clearly linked to the data in the table. A conclusion may be provided, but it is not justified.

3-4

Level 1: Some correct points are made that support and do not support the conclusion.

1-2

No relevant content

0

Indicative content

• for the elements in Period 2 conductivity increases from Li (one delocalised electron per atom) to Be (two delocalised electrons per atom)
• for the elements in Period 3, conductivity increases from Na (one delocalised electron per atom) to Mg (two delocalised electrons per atom) to Al (three delocalised electrons per atom)
• Zn has two delocalised electrons per atom, but its conductivity is less than those of Li and Na (one delocalised electron per atom each)
• the first two pieces of evidence above support the statement, but the third does not
• reasoned decision, drawing on all of the above evidence

06.1

Level 3: A detailed and coherent answer is given, using suitable examples and the data in the table. A conclusion is provided and justified using the data.

5-6

AO1 × 3

AO3 × 3

4.2.2.3

Level 2: A detailed and coherent answer is given, using suitable examples and the data in the table. Some electron configurations maybe be incorrect. A conclusion is provided and justified using the data.

3-4

Level 1: Some correct points are made that support the conclusion.

1-2

No relevant content

0

Indicative content

• calcium and magnesium are in Group 2, so form ions with +2 charge
• oxygen and sulfur are in Group 6, so form ions with -2 charge
• bromine is in Group 7, so form ions with -1 charge
• sodium is in Group 1 and forms ions with +1 charge
• compounds with two ions with double-charges have higher melting points than those with single-charges
• compounds with +1 and -2 ions have higher melting points than compounds with +2 and -1 ions
• compounds with two ions with single charges have higher melting points that those with +2 and -1 ions

06.2

in general, the greater the charge of the ions of a compound, the higher the melting point

because there is a greater electrostatic attraction between the ions/more energy is needed to break the bonds

1

1

AO3

4.2.2.3

07.1

electrons transferred from magnesium to bromine

magnesium atom loses 2 electrons

2 bromine atoms gain 1 electron each

1

1

1

AO1

4.2.1.2

07.2

Mg²⁺ ions

Br^– ions

1

1

AO2

4.2.1.2

07.3

MgBr₂

1

AO1

4.2.1.2

07.4

three from:

• solid at room temperature
• high melting and boiling points
• conducts electricity when molten or in solution
• soluble in water

3

AO1

4.4.2.3

08.1

ionic compound

conducts in the liquid state, but not the solid state

high melting point

2

AO1 × 1

AO2 × 1

4.2.2.3

08.2

B and D

both can conduct electricity in the solid and liquid states

1

1

AO1 × 1

AO2 × 1

4.2.2.8

08.3

melting point is low

metals have giant structures of atoms bonded with strong metallic bonding

so normally lots of energy needed to separate the atoms/most metals have a high melting point

1

1

1

AO2

4.2.2.7

09.1

Cl atoms should have 7 dots and 1 cross. O atom should have 6 crosses and 2 dots.

the O atom should be in between 2 Cl atoms. The Cl atoms should be sharing 1 cross and 1 dot each with the O atom.

2

AO2

4.2.1.4

09.2

in dichlorine monoxide, an electron from each chlorine atom joins with an electron the the oxygen atom

to form two shared pairs of electrons or two covalent bonds

in caesium oxide, the one electron from the outermost shell of two caesium atoms

is transferred to the oxygen atom

creating a strong electrostatic attraction between the two ions

1

1

1

1

1

AO1

4.2.1.3

4.2.1.4

09.3

CsO has high melting and boiling points

because large amounts of energy are needed to break the multiple strong ionic bonds

Cl₂O has low melting and boiling points

because only weak intermolecular forces must be overcome when the substance melts or boils, so little energy is required

or

CsO conducts electricity in the liquid state and when dissolved in water

because its charged particles/ions are then free to move

Cl₂O does not conduct electricity in any state

because the molecules do not have an overall electric charge

1

1

1

1

or

1

1

1

1

AO2

4.2.2.3

4.2.2.4

09.4

barium ions have a larger/double charge/are 2+ ions

so the attraction between the Ba²⁺ and O^2- ions is greater than the attraction between Cs⁺ and O^2- ions (or reverse argument)

1

1

AO3

4.2.2.3

10.1

K ion should be in square brackets with a ‘+’ in superscript after the brackets. There should be a 2 before the brackets

O ion should have 6 crosses and 2 dots in square brackets with a ‘+’ in superscript after the brackets.

K⁺ and O²⁻

two marks for diagram

one mark for both formulae

3

AO2

4.2.1.2

10.2

regular structure (giant ionic lattice)

strong electrostatic forces of attraction in all directions

between oppositely charged potassium and oxygen ions

1

1

1

AO1

4.2.1.3

10.3

oxygen is a simple molecule

mare held together by weak intermolecular forces

so lower amounts of energy are needed to separate them

potassium oxide ions are held together by strong electrostatic forces

so greater amounts of energy are needed to separate them.

1

1

1

1

1

AO1

4.2.2.3

4.2.2.4

10.4

metallic bonds are weaker than ionic bonds

1

AO3

11.1

RbCl

1

AO3

4.2.1.3

11.2

add another layer of ions above or below the given cube

there would then be 18 of each type of ion.

1

1

AO3

4.2.1.3

11.3

two from:

• assumes ions are spheres
• assumes there is a large amount of space between each ion
• assumes ions do not overlap

AO2

4.1.1.5

12.1

Ca²⁺

1

AO2

4.2.1.2

12.2

O^2-

one mark for charge

one mark for formula written correctly

2

AO2

4.2.1.2

12.3

Level 3: The properties are clearly described, and correct reasons are given for each of these properties. The descriptions and reasons are coherently written.

5–6

AO1

4.2.2.3

Level 2: All the properties are clearly described, but reasons are not given for them or some of the properties are clearly described and reasons are given for each of them.

3–4

Level 1: Some correct points are made. The answer lacks coherence and explanations are not clearly linked to descriptions of properties.

1–2

No relevant content

0

Indicative content

• high melting point – large amounts of energy needed to break the many strong bonds/strong electrostatic forces of attraction
• high boiling point – large amounts of energy needed to break the many strong bonds/strong electrostatic forces of attraction
• conducts electricity in liquid state or in solution – has charged particles/ions that are then free to move (so that charge can flow)
• does not conduct electricity in solid state – its charged particles/ions are not free to move (so charge cannot flow)

13.1

A: gas

D: liquid

1

1

AO2

4.2.2.1

13.2

high melting and boiling point

conducts electricity when solid and liquid

1

1

AO2

4.2.2.7

13.3

C

sodium chloride is an ionic compound

high melting point

only conducts electricity when liquid

1

1

1

1

AO2

4.2.2.3

13.4

A

1

AO2

4.2.2.4

13.5

covalent bonds

small molecule/simple molecular

1

1

AO2

4.2.2.4

14.1

29

1

AO2

4.1.1.5

14.2

36

1

AO2

4.1.1.5

14.3

63

1

AO2

4.1.1.5

14.4

27

1

AO2

4.1.1.5

14.5

1

1

1

AO1 × 1

AO2 × 3

4.1.1.5

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

metal

1

AO1

4.1.2.3

01.2

rubidium hydroxide and hydrogen

1

AO2

4.1.2.5

01.3

rubidium + oxygen → rubidium oxide

1

AO1

4.1.2.5

01.4

2Na(s) + Br₂(l) → 2NaBr(s)

one mark for balancing

one mark for state symbols

2

AO2

4.1.2.5

01.5

rubidium is more reactive that sodium/sodium less reactive

because it is further down Group 1/it has more electron shells

outer electron is further from the nucleus / the nucleus is more shielded

so easier to transfer to bromine/easier to remove

1

1

1

1

AO1

4.1.2.5

02.1

gaps were left for elements that were predicted to exist, but had not yet been discovered

in some places, the order of the elements were changed (based on atomic weights)

1

1

AO1

4.1.2.2

02.2

elements could be arranged in order of atomic/proton number

so elements were grouped according to their chemical properties.

1

1

AO1

4.1.2.2

02.3

elements in the same group of the Periodic Table have the same number of electrons in their highest energy level/outer shell

number of electrons in the highest energy level/outer shell determine the chemical properties of an element

1

1

AO1

4.1.2.2

02.4

the existence of neutrons makes possible the existence of isotopes

1

AO2

4.1.2.2

03.1

Group 0: inert

Group 1: react with water to make alkaline solutions

Group 7: react with metals to make ionic compounds

one mark for each correct match

3

AO2

4.1.2.5

03.2

Level 3: Clearly links trend in reactivity for both groups to electron structure.

5-6

AO2

4.2.2.3

Level 2: Clearly links trend in reactivity for one group to electron structure OR correctly states trends in reactivity for both groups.

3-4

Level 1: Correctly states trends in reactivity for one/both groups.

1-2

No relevant content

0

Indicative content

• Group 1 gets more reactive down the group
• Group 1 loses outer electron to form full outer shell/nearest noble gas
• electron is further from the nucleus, so becomes easier to remove
• Group 7 gets less reactive down the group
• Group 7 atoms gain electron to form full outer shell/nearest Noble Gas
• less attraction felt by positive nucleus charge further away from nucleus.

03.3

inert/unreactice

because atoms already have a full outer electron shell

ignore references to heavier Noble Gases forming some compounds

1

1

AO1

4.1.2.4

04.1

outer electrons of xenon are far way from the nucleus

weaker electrostatic force between outer electrons and positively charged nucleus

strong attraction from the positively charged fluorine nucleus

1

1

1

AO3

4.1.2.4

4.1.2.6

04.2

Xe atom should have 8 black dots and 4 green dots. F atoms should have 8 black dots.

each F atoms should share 2 black dots with the Xe atom

2

AO3

4.2.1.4

04.3

covalent

1

AO1

4.2.1.4

05.1

Group 1

1

AO1

4.1.2.5

05.2

so that the big lump of sodium does not react with oxygen/water from the air

1

AO3

05.3

to avoid sodium reacting with water on fingers/to prevent injury to the hand

1

AO3

05.4

use filter paper to remove the oil from the surface of the sodium/scrape the surface of the sodium to expose the metal or remove some sodium oxide

1

AO3

05.5

hydrogen/H₂.

reject H

1

AO1

4.1.2.5

05.6

add universal indicator to the water

colour change from green to blue/purple

allow other indicators provided correct colour change given

1

1

AO1

4.1.2.5

05.7

atoms of all Group 1 elements lose an electron in their reactions

atoms get bigger down the group, so the outer electron is further from the nucleus/Na has an extra shell/Li has one fewer shell

electrostatic force of attraction between positive nucleus and negatively charged electron decreases down the group

so it is easier to lose electron/transfer electron

allow references to shielding

one mark for each part of the explanation

3

AO1

4.1.2.5

5.8

very vigorous reaction/caesium catches fire/very vigorous bubbling

allow any correct observations

allow damage to glass trough answers only if they are related to the high reactivity of Cs

1

AO2

4.1.2.5

06

Level 3: Solutions X, Y and Z are correctly identified, and the justification is correct and explained coherently and logically.

5-6

AO3

4.1.2.6

Level 2: Solutions X, Y and Z are correctly identified, and some aspects of the justification are correct. The explanation lacks coherence and logic.

3-4

Level 1: One or two solutions are correctly identified, and one or two points of explanation are made. The explanation lacks coherence and logic.

1-2

No relevant content

0

Indicative content

• X is potassium bromide, Y is potassium chloride, Z is potassium iodide
• a Halogen displaces a less reactive Halogen from an aqueous solution of its salt
• chlorine is more reactive than bromine, so chlorine displaces bromine from potassium bromide solution (solution X) and iodine from potassium iodide solution (solution Z)
• bromine is more reactive than iodine, so bromine displaces iodine from potassium iodide solution (solution Z)
• iodine is less reactive than both chlorine and bromine, so displaces neither of these compounds from solutions of their salts

07

Level 3: The prediction is correct, and the explanation is clear, coherent and logical.

5-6

AO1 × 5

AO3 × 1

4.1.2.5

4.1.2.6

Level 2: The prediction is correct, but the explanation lacks some clarity and coherence.

3-4

Level 1: The prediction is incorrect, but one or two aspects of the explanation are correct.

1-2

No relevant content

0

Indicative content:

• D – sodium and fluorine
• fluorine is most reactive of the Halogens given and sodium is most reactive of the Alkali Metals given
• in the reaction, each fluorine atom gains an electron and each sodium atom loses an electron.
• fluorine atom attracts electrons to it more strongly than bromine because its atoms are smaller
• so incoming electrons are attracted to the nucleus more strongly
• sodium loses its electrons more easily than lithium because its atoms are bigger
• so the outer shell/highest energy level electrons are less strongly attracted to the nucleus

08.1

Noble Gases

1

AO1

4.1.2.4

08.2

A

1

AO2

4.1.2.4

08.3

A

1

AO2

4.1.2.4

08.4

Ne atom should have 2 rings with 2 dots on the first ring and 8 dots on the second ring

1

AO1

4.1.2.4

08.5

their atoms have a full outer shell of electrons/highest energy level/stable electron arrangement

1

AO2

4.1.2.4

09.1

B

1

AO2

4.1.2.1

09.2

C

because its outer electron shell/highest energy level is full/atoms have stable arrangement of electrons

1

1

AO2

4.1.2.4

09.3

A and D

both required for the mark

1

AO2

4.1.2.1

10.1

increases

because, like Group 1, atoms of Group 2 elements react by losing electrons

atoms get bigger down the group, so the outer electrons are further from the nucleus

so the force of attraction between the nucleus and the outer electrons decreases.

no mark for ‘increases’ alone

1

1

1

1

AO2 × 2

AO3 × 2

4.1.2.5

10.2

giant (metallic) structures

atoms arranged in regular pattern

electrons of outer shells of atoms delocalised and free to move throughout the whole structure

1

1

1

AO1

4.2.1.5

10.3

less

sodium reacts vigorously with cold water.

1

1

AO3

4.1.2.5

10.4

MgCl₂

1

AO3

4.1.2.5

11.1

H atom should have 1 dot and 1 cross. F atom should have 7 crosses and 1 dot.

H atom and F atom should be sharing one dot and one electron.

2

AO2

4.1.2.6

4.2.1.4

11.2

Level 3: The electronic structures are correctly stated or drawn, and the explanation is clear, coherent and logical.

5-6

AO2

4.1.2.6

Level 2: The electronic structures are correctly stated or drawn, but the explanation lacks some clarity and coherence.

3-4

Level 1: One of the electronic structures are correctly stated or drawn, and one or two parts of an explanation are included.

1-2

No relevant content

0

Indicative content:

• correctly stated or drawn electronic structures of fluorine (2,7) and chlorine (2,8,7) atoms
• atoms of fluorine and chlorine gain an electron in their reactions.
• chlorine is bigger than fluorine, so its outer electrons are

further from nucleus

• electrostatic force of attraction between positive nucleus and incoming negatively charged electron is greater for fluorine than chlorine

11.3

products of reaction three melts at higher temperature.

product of reaction two has small molecules/simple molecules, so low melting point

product of reaction three has (giant) ionic structure, so high melting point

one mark for correct suggestion, one mark for reason

1

1

1

AO2 × 2

AO3 × 1

4.1.2.6

12.1

Alkali Metals

1

AO1

4.1.2.6

12.2

they have the same number of electrons in the shell furthest from the nucleus

1

AO1

4.1.2.1

12.3

metals

1

AO1

4.1.2.3

12.4

caesium bromide

1

AO2

4.1.2.5

4.1.2.6

13.1

B

1

AO2

4.2.2.1

13.2

2,8,8

1

AO2

4.1.1.7

13.3

one electron from potassium’s outer shell

is transferred to chlorine’s outer shell

to form +1 potassium ion and -1 chlorine ion

electrostatic attraction occurs between oppositely charged ions

1

1

1

1

AO2

4.2.1.2

13.4

ions/charges are free to move

1

AO2

4.2.2.3

13.5

place solution in round-bottom flask

and attach this round-bottom flask to condenser

heat this round-bottom flask with a Bunsen burner

water will evaporate and condense in the condenser

this can be collected in a separate vessel.

potassium chloride will remain in the round-bottom flask.

1

1

1

1

1

1

AO1

4.1.1.2

14.1

discovery of neutrons led to discovery of isotopes

explained why atomic weight order was not correct

1

AO1

4.1.2.2

14.2

has one electron in the outermost shell.

does not share properties with the rest of Group 1 elements

accept a named property

1

1

AO3

4.1.2.5

14.3

number of protons

1

AO1

4.1.1.5

14.5

1

1

1

AO2

4.1.1.6

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

whether or not it conducts electricity

1

AO3

4.1.3.1

01.2

B

iron is a transition metal

B has properties that are typical of a transition metal (forms a coloured compound/reacts less vigorously with water).

1

1

1

AO2 × 2

AO3 × 1

4.1.3.1

4.1.3.2

01.3

FeO contains the Fe²⁺ ion and Fe₂O₃ contains the Fe³⁺ ion

so iron forms ions with different charges/transition metals can have different oxidation states

1

1

AO1 × 1

AO2 × 1

4.1.3.2

02.1

fine particles: 100 to 250 nm

nanoparticles: 1 to 100 nm

coarse particles: 2.5×10^-6 m to 1×10^-5 m

3

AO1

4.2.4.1

02.2

3.4×10^-6 m

1

AO2

4.2.4.1

02.3

coarse particle

accept if the coarse particle range was assigned to another particle type in question 02.1, and that particle type is given here

accept ‘coarse particle’ if answer to question 02.1 is incorrect

1

AO2

4.2.4.1

02.4

high surface area to volume ratio

which means that a greater proportion of atoms are at the surface

1

1

AO1

4.2.4.1

03.1

independent: metal

dependent: diameter of indentation

1

1

AO2

03.2

so that the test is fair/is a fair comparison

1

AO1

03.3

so that it can make indentations in hard metals

one mark for each correct match

1

AO2

03.4

measure the diameter of the indentation in different places and calculate the mean

allow ‘average’ rather than ‘mean’

1

AO3

03.5

A

gave the smallest indent

and is therefore the hardest metal

1

1

1

AO3

04.1

nanoparticles have high surface area to volume ratio

nanoparticles are smaller, so can enter cells more easily

1

1

AO2

4.2.4.1

04.2

nanoparticles may enter human cells and cause harm

1

AO3

4.2.4.2

04.3

at concentrations up to and including 1.2 g/cm³, silver nanoparticles do not kill bacteria/minimal effect of bacteria

from a concentration of 1.2 g/cm³ upwards, as concentration increases, the percentage of bacteria that survive decreases

1

1

AO2

04.4

two from:

• sun creams
• deodorants
• catalysts
• electronics
• cosmetics

allow any other valid answer

2

AO1

4.2.4.2

05.1

8.9 g/cm³

one for correct value

one for correct unit

2

AO2

05.2

7 (g/cm³)

one for correct value

ignore units

1

AO2

05.3

B and C

both letters required for the mark

1

AO2

4.1.3.1

05.4

use a measuring cylinrer instead of a beaker.

1

AO3

05.5

lithium reacts with water

1

AO2

4.1.2.5

5.6

one for correct calculation of volume

one for correct substitution and answer

one for giving answer to two significant figures.

3

AO2

06.1

rhodium

1

AO2

4.1.3.2

06.2

lithium

1

AO2

4.1.3.1

06.3

iron

1

AO2

4.1.3.1

06.4

vanadium

1

AO2

4.1.3.1

06.5

copper

1

AO2

4.1.3.2

07.1

E and F

both letters required for the mark

1

AO1

4.1.2.4

4.1.2.6

07.2

A and E

both letters required for the mark

1

AO2

4.1.2.5

4.1.2.6

07.3

Level 3: A detailed and coherent comparison is given, demonstrating a sound knowledge of the properties of Group 1 elements and transition metals.

5-6

AO1×5

AO2×1

4.1.2.5

4.1.3.1

Level 2: Correct properties are listed for element B/Group 1 elements and element D/transition elements. Some comparisons are made, but not all are clearly articulated.

3-4

Level 1: Some properties are listed for element B/Group 1 elements and element D/transition metals. Few comparisons are made, and these are not clearly articulated.

1-2

No relevant content

0

Indicative content

• both elements conduct electricity
• B has a lower melting point than D
• B has a lower density than D
• D is stronger than B
• D is harder than B
• B reacts more vigorously than D with oxygen
• B reacts with water to make hydrogen and an alkaline solution/hydroxide
• B reacts more vigorously than D with halogens
• D does not react with water

08.1

surface area = 3 nm × 3 nm × 6 = 54 (nm²)

volume = 3 nm × 3 nm × 3 nm = 27 (nm³)

surface area to volume ratio = 54:27 = 2 (nm^-1)

units are not required.

1

AO1 × 1

AO2 × 2

4.1.2.4

08.2

because of the high surface area to volume ratio of the nanoparticle material/a greater number of atoms are exposed

1

AO1

4.2.4.1

09.1

its diameter is not in the range of 1 to 100 nm

1

AO1

4.2.4.1

09.2

2.75×10^-10 m

one for correct answer

one for correctly writing answer in standard form

2

AO2

09.3

number of particles on one face = 287² = 82 574

to one significant figure in standard form, answer = 8×10⁴

one for working

one for correct answer

one for giving answer to one significant figure

one for standard form

4

AO2

10

Level 3: Data that support the statement and data that do not support the statement are identified, and a judgement made and justified.

5-6

AO2×1

AO3×5

4.1.2.5

4.1.3.1

Level 2: Data that that support the statement and data that do not support the statement are identified, but no overall judgement is made.

3-4

Level 1: Some data that support the statement and some data that do not support the statement are identified.

1-2

No relevant content.

0

Indicative content

• caesium, lithium and sodium are in Group 1, while copper, gold and iron are transition metals
• all the transition elements have much higher melting points than the Group 1 elements, supporting the statement
• two of the transition elements, copper and gold, have relative conductivities that are at least twice as high as those of the three Group 1 elements, supporting the statement
• the relative conductivity of iron is less than the conductivities of two of the Group 1 elements (lithium and sodium), which does not support the statement

allow ‘conductivity’ for ‘relative conductivity’ throughout.

11.1

electron: -1

neutron: 0

proton: +1

1

1

1

AO1

4.1.1.4

11.2

proton

1

AO1

4.1.1.4

11.3

8

1

AO1

4.1.1.5

11.4

chlorine exists as multiple isotopes

with different numbers of neutrons

1

1

AO1

4.1.1.5

11.5

2,8,5

1

AO1

4.1.1.7

12.1

giant structure, so higher melting and boiling points

delocalised electrons mean that it can conduct electricity

chlorine is made of small molecules

with weak intermolecular forces, so lower melting and boiling points

no electrical charge/electrons or ions are not free to move, so cannot conduct electricity

1

1

1

1

1

4.1.2.5

4.2.1.3

4.2.2.3

4.2.2.4

4.2.2.7

12.2

Level 3: The descriptions of structure and bonding is correct, clear, detailed and coherent. The reason for its high melting point is clearly explained.

5-6

AO1

4.2.1.3

4.2.2.3

Level 2: The descriptions of structure and bonding are correct, but lack some detail and clarity. The reason for its high melting point is outlined.

3-4

Level 1: Some correct points about the structure and bonding are made, but they lack detail and clarity. The reason for its high melting point is outlined.

1-2

No relevant content.

0

Indicative content

• sodium chloride consists of sodium ions with a single positive charge and chloride ions with a single negative charge
• the ions are arranged in a regular lattice.
• there are strong electrostatic forces of attraction between oppositely charged ions
• the electrostatic forces of attraction act in all directions
• it has a high melting point because of the large amount of energy needed to break the many strong bonds

12.3

2Na(s) + Cl₂(g) → 2NaCl(s)

3

AO2

4.1.1.1

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

12 + (4 × 1) = 16

1

AO2

4.3.1.2

01.2

the reactant that is completely used up when the other reactant is present in excess

1

AO1

4.3.2.1

01.3

CH₄ + 2O₂ → CO₂ + 2H₂O

2

AO2

4.3.1.1

01.4

oxygen

1

AO2

4.3.2.4

01.5

0.25

1

AO2

4.3.2.4

02.1

1

1

AO1

4.3.2.1

02.2

164

1

AO2

4.3.1.2

02.3

gaseous products leave the test tube as a gas

allow named gas (oxygen or nitrogen dioxide).

1

AO2

4.3.1.3

02.4

CaO: (40 + 16) = 56

= 0.4 mol

0.4 x 164

= 65.6g 6.02 x 10²³

1

1

1

1

1

AO1x1

AO2x4

4.3.2.2

03.1

mass of one mole of water = RMM of H₂O = 16 + (2 x 1) = 18

answer states for water, 1 g = 1 cm³, so 1 mole = 18 g = 18 cm³

1

1

AO2

4.3.2.1

03.2

= 2.99×10^-23 g

1

1

AO2

4.3.2.1

03.3

answer assumes that all particles in the 18 cm³ is taken up by water particles

but water is a liquid, so has space between the particles

1

1

AO3

4.3.2.1

04.1

there are three atoms of oxygen for every one atom of sulfur

1

AO2

4.1.1.1

04.2

32 + (2 x 16) = 64

accept correct answer without working shown

1

AO2

4.3.1.2

04.3

1.68 – 1.28 = 0.4 g

accept correct answer without working shown

1

1

AO1

4.3.1.1

05.1

the number of atoms, molecules or ions in a mole of a given substance

accept ‘particles’ in place of ‘atoms’, ‘molecules’ or ‘ions’

accept mention of just one or two of atoms, molecules or ions.

1

AO1

4.3.2.1

05.2

M_r of water = (2 x 1) + 16 = 18

number of molecules = 12.89 x 6.02×10²³

= 7.76×10²⁴

1

1

1

1

1

AO2

4.3.2.1

05.3

2 x 7.76×10²⁴ = 1.55×10²⁵

1

1

AO2

4.3.2.1

06.1

one from

• wear eye protection
• work in a fume cupboard

accept any other reasonable answer.

1

AO3

WS2.4

06.2

2Na(s) + Cl₂(g) → 2NaCl(s)

one mark for balancing

one mark for state symbols

2

AO2

4.3.1.1

4.2.2.2

06.3

Level 3: The description is detailed and accurate. The writing is clear, coherent and logical.

5-6

AO1

4.2.1.2

4.2.1.3

Level 2: The description is correct, although lacks detail. The writing is mainly clear, although the structure may lack logic.

3-4

Level 1: Some aspects of the description are correct. The writing lacks clarity, coherence and logic.

1-2

No relevant content.

0

Indicative content

• sodium atoms each lose one electron to make Na⁺ ions.
• chlorine atoms each gain one electron to make Cl^– ions.
• the oppositely charged ions are held together
• in a lattice
• by strong electrostatic forces of attraction
• that act in all directions.

07.1

1

AO2

MS2b

07.2

56 – 48 = 8

1

AO2

4.3.1.4

07.3

1

AO2

4.1.3.4

07.4

= 0.1825

= 0.18

1

1

1

AO2

4.3.2.5

08.1

HNO₃(aq) + KOH(aq) → KNO₃(aq) + H₂O(l)

1

AO2

4.2.2.2

08.2

allow 0.02 g/cm³ if units are specified.

1

1

AO2

4.3.2.5

08.3

1

1

AO2

4.3.2.5

08.4

1

1

1

1

1

1

AO2

4.3.2.5

09.1

first N atom should have 2 shells with 2 crosses in first shell and 5 crosses in second shell, second N atom should be the same but with dots.

the N atoms should be sharing 3 dot and 3 cross electrons in an alternating pattern.

2

AO2

4.2.1.4

09.2

gas would build up in the tube, as it has nowhere to escape to

this may result in the bung being forced out of the test tube

1

1

AO3

WS2.3

WS2.4

09.3

1

1

1

1

1

AO2×3

AO3×2

4.3.2.3

10.1

500 mg x 5 = 2500 mg in 1 dm³

0.5 g/dm³

1

1

1

AO2

WS4.3

WS4.4

WS4.5

4.3.2.5

10.2

(8 x 12) + (9 x 1) + 14 + (2 x 16) = 151 g

1

AO2

4.3.1.2

10.3

M_r of ibuprofen = (13 x 12) + (18 x 1) + (2 x 16) = 206

number of moles in 1000 cm³ of solution = 0.000 485 x 200

= 0.0971 moles

or 9.71×10^-2 mol in standard form

final mark awarded for giving answer to 3 significant figures

1

1

1

1

AO2

4.3.2.1

4.3.2.5

MS2a

11.1

(4 x 12) + (2 x 1) + 56 + (4 x 16) = 170

1

AO2

4.3.1.2

11.2

M_r = 56 + 32 + (4 x 16) = 152

= 4.3 x10^-4 moles

one mark awarded for giving answer to two significant figures; one mark for correctly expressing answer in standard form

1

1

2

AO2

4.3.2.1

MS1b

11.3

M_r = (12 x 12) + (24 x 1) + 56 + (14 x 16) = 448

number of moles of iron = 0.000 670

mass of iron = 0.000 670 x 56 = 0.0375 g

or 37.5 mg if correct units are given

1

1

1

1

AO2×2

AO3×2

4.3.2.1

MS2a

12.1

M_r of iron oxide = (56 x 2) + (3 x 16) = 160

0.10 moles of Fe₂O₃ reacts with 0.15 moles of C

12 x 0.15

= 1.8 g

1

1

1

1

1

AO2

4.3.2.2

12.2

number of moles of CO₂ = number of moles of C = 0.15

M_r of CO₂ = 12 + (2 x 16) = 44 g

mass of CO₂ = 0.15 x 44 g

= 6.6 g

1

1

1

1

AO2

4.3.2.2

12.3

3.7 tonnes = 3700 kg

= 23.125 moles

23.125 x 2 = 46.25 moles of Fe

46.25 x 56

= 2590 kg

1

1

1

1

1

1

AO2

4.3.2.2

12.4

= 70%

1

1

AO2

13.1

wear eye protection

work in a fume cupboard

1

1

AO1

WS2.4

13.2

fill the gas jar with chlorine gas first

so that the chlorine does not escape before the sodium is added to it

1

1

AO3

WS2.4

13.3

Na ion should have 2 shells with 2 crosses in the first shell, 8 crosses in second shell. Should be in square brackets with a superscript ‘+’ to the right of the brackets.

Cl ion should have 3 shells with 2 dots in the first shell, 8 dots in the second shell and 7 dots and 1 cross in square brackets. Should be in square brackets with a superscript ‘+’ to the right of the brackets.

2

AO1

4.2.1.2

three from:

• ionic bonding
• sodium atom transfers 1 electron to chlorine atom
• forming 1+ sodium ion and -1 chlorine ion
• electrostatic attraction between oppositely charged ions

one mark for each correct point

3

AO1

4.2.1.2

13.5

sodium conducts electricity

because it contains delocalised electrons that can move

chlorine does not conduct electricity

because it does not contain charged particles that can move

sodium chloride conducts electricity when in solution or molten, but not when solid

because ions are free to move

1

1

1

1

1

1

AO1

4.2.1.3

4.2.1.4

4.2.1.5

13.6

at the start, orange-brown liquid instead of green gas during/reaction would be less vigorous

1

AO1

4.1.2.6

14.1

P atom should have 3 shells, first shell should have 2 crosses, second shell should have 8 crosses and 3 shell should have 5 crosses

1

AO1

4.1.1.7

14.2

five

1

AO3

4.1.2.1

14.3

Level 3: The properties and locations are correctly given. The comparisons are clear, coherent and logically expressed.

5-6

AO1

4.1.1.5

4.1.1.4

Level 2: The properties and locations are mainly correct. The comparisons are mainly clear, but there is a lack of logic in the answer.

3-4

Level 1: Some of properties and/or locations are correct. The writing lacks clarity, coherence and logic, and only one or two comparisons are made.

1-2

No relevant content.

0

Indicative content

• protons have a charge of +1 and a relative mass of 1
• neutrons have no charge and a relative mass of 1
• electrons have a charge of −1 and a very small relative mass
• protons and neutrons are found in the nucleus of an atom
• electrons are found outside the nucleus
• electrons are in orbits/shells/levels

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

percentage yield:

atom economy:

1

1

AO1

4.3.3.1

4.3.3.2

01.2

two from:

• sustainable development/preserves Earth’s resources
• economic reasons
• reduce waste

1

1

AO1

4.3.3.2

01.3

some remains on the filter paper/is not scraped off

1

AO3

02.1

two from:

• wear eye protection
• use a safety screen between students and reaction
• stand back immediately when reaction starts

allow any other suitable precaution

1

1

AO3

02.2

from balanced equation, one mol of iron(III) oxide reacts with two mol of aluminium, so 0.050 mol of iron(III) oxide needs 0.10 mol of aluminium.

1

1

1

1

AO2

4.3.2.1

4.3.2.4

02.3

from balanced equation, one mol of iron(III) oxide makes two mol of iron,

so 0.050 mol of iron(III) oxide makes 0.10 mol of iron

this has a mass of 0.10 × 56 = 5.6 g

1

1

AO2

4.3.2.1

02.4

percentage yield:

allow error carried forward

1

AO1 x 1

AO2 x 1

4.3.3.1

02.5

some of the aluminium reacts with oxygen from the air

some of the iron made is not collected

allow other suitable reasons

1

1

AO3

4.3.3.1

03.1

1

1

1

1

1

AO1 x 1

AO2 x 4

4.3.4

03.2

M_r of H₂SO₄ = (2 × 1) + 32 + (4 × 16) = 98 g

mass of 0.0500 mol = 0.0500 × 98 g = 4.9 g,

so concentration = 4.9 g/dm³

1

1

AO2

4.3.2.1

03.3

M_r of NaOH = 23 + 16 + 1 = 40 g

mass of 0.0100 mol = 40 × 0.100 = 4.0 g

1

1

AO2

4.3.2.1

04.1

M_r of C₂H₅OH = (2 × 12) + (5 × 1) + 16 + 1 = 46

1

AO2

4.3.1.2

04.2

the atom economy process of 1 is approximately double that of process 2

1

1

1

AO2

4.3.3.2

04.3

Level 3: The comparisons are detailed and accurate. The writing is clear, coherent and logical and comparisons are clearly made.

5-6

AO3

4.3.3.2

Level 2: The comparisons are generally correct, although may lack detail. The writing is mainly clear, although the structure may lack logic and comparisons are not always clear.

3-4

Level 1: Some comparisons are correct. The writing lacks clarity, coherence and logic, and the comparisons are not clearly expressed.

1-2

No relevant content

0

Indicative content

• 1 occurs at a higher temperature and pressure than 2, so 2 is better for sustainable development in this respect
• the raw material for 1 is obtained from crude oil, so 2 is better for sustainable development in this respect
• 2 produces carbon dioxide, which is a greenhouse gas, so 1 is better for sustainable development in this respect
• 1 has a higher atom economy than 2, so 1 is better for sustainable development in this respect

05.1

M_r = (3 × 12) + (8 × 1) = 44

at room temperature and pressure, one mol of gas occupies 24 dm³

136 mol occupies 136 × 24 = 3264 dm³

1

1

1

1

AO1×1

AO2×3

4.3.5

05.2

50 × 5 = 250 cm³

1

1

AO1×1

AO2×1

4.3.5

05.3

from balanced equation, one mol of propane makes three mol of CO₂

number of mol of CO₂ = 3 × 10.9 = 32.7 mol

24 × 32.7 = 784.8 dm³

= 785 dm³

1

1

1

1

AO1 × 2

AO2 × 3

4.3.5

06.1

8.8 g

1

AO2

4.3.1.1

4.3.3.1

06.2

8.2 g

1

AO2

4.3.3.1

06.3

100%

1

AO2

4.3.3.2

07

Level 3: Appropriate equipment named and a detailed description of the various repeats required is provided.

5-6

AO1

4.4.2.5

Level 2: Method provided. Some attempt at demonstrating need for repeats.

3-4

Level 1: A basic titration method provided. No mention of repeats.

1-2

No relevant content.

0

Indicative content

• use a pipette to measure out a known volume of sodium hydroxide.
• put the sodium hydroxide into a conical flask.
• add a few drops of a suitable indicator to the conical flask
• place the conical flask on a white tile.
• fill a burette with the hydrochloric acid.
• add about one m³ of acid to the conical flask and mix by swirling the flask.
• repeat until the indicator changes colour.
• record the volume of acid used as the rough titre.
• repeat the process, but as the end point is approached, add the acid drop wise to obtain a precise measurement.
• repeat until at least two concordant results are achieved.

08.1

M_r of CH₄ = 12 + (4 × 1) = 16

M_r of H₂O = (1 × 2) + 16 = 18

atom economy:

1

1

1

AO1 × 1

AO2 × 2

4.3.3.2

08.2

use electricity generated from renewable resources

allow suitable alternative answers

1

AO3

08.3

Level 3: The comparisons are detailed and accurate. The writing is clear, coherent and logical and comparisons are clearly made.

5-6

AO3

4.3.3.2

Level 2: The comparisons are generally correct, although may lack detail. The writing is mainly clear, although the structure may lack logic and comparisons are not always clear.

3-4

Level 1: Some comparisons are correct. The writing lacks clarity, coherence and logic, and the comparisons are not clearly expressed.

1-2

No relevant content

0

Indicative content

• 1 occurs at a higher temperature than 2, so 2 is better for sustainable development in this respect
• if the raw material for 1 is obtained from fossil fuels, 2 is better for sustainable development in terms of resources used
• if the material for 1 is obtained from sewage, both processes have a similar impact on the environment in terms of resources used
• 2 produces carbon monoxide, which is poisonous, so 1 is better for sustainable development in terms of pollutants made
• 1 has a higher atom economy than 2, so 1 is better for sustainable development in this respect

09.1

to allow oxygen to enter the crucible

1

AO3

09.2

percentage yield:

1

1

1

AO1 × 1

AO2 × 2

4.3.3.1

09.3

one from:

• some magnesium oxide escaped out of the crucible
• not all the magnesium reacted
• some of the magnesium oxide reacted with nitrogen from the air

allow other suitable answers

1

AO3

4.3.3.1

10.1

13.55

1

AO3

4.4.2.5

10.2

13.00

1

AO2

4.4.2.5

10.3

HNO₃(aq) + NaOH(aq) → NaNO₃(aq) + H₂O(l)

1 mark for reactants, 1 mark for products, 1 mark for state symbols

3

AO2

4.4.2.5

10.4

converting units, 25 cm³ = 0.025 dm³ and 13cm³ = 0.013 dm³

moles of NaOH = 0.1 × 0.025 = 2.5×10^-3

accept errors carried forward for ratios from question 10.3

1

1

1

1

AO1

AO2

4.4.2.5

11.1

F

1

AO1

4.1.2.1

4.1.2.5

11.2

two from

• A
• B
• C
• D

two correct letters required for the mark

1

AO1

4.1.2.3

11.3

Level 3: The description is detailed and accurate. The writing is clear, coherent and logical.

5-6

AO1

4.1.2.2

Level 2: The description is correct, although lacks detail. The writing is mainly clear, although the structure may lack logic.

3-4

Level 1: Some aspects of the description are correct. The writing lacks clarity, coherence and logic.

1-2

No relevant content

0

Indicative content

• before discovering sub-atomic particles, scientists attempted to classify the elements by arranging them in order of their atomic weights
• early periodic tables were incomplete, and some elements were placed in inappropriate groups
• Mendeleev overcame the problems by leaving gaps for elements that he thought had not been discovered
• Mendeleev also changed the order of elements in some places based on atomic weights
• elements predicted by Mendeleev were discovered and filled the gaps
• knowledge of isotopes made it possible to explain why the order based on atomic weights was not always correct

12.1

A

1

AO3

4.2.1.4

12.2

one dot and one cross in each of the four intersections

2

AO1

4.2.1.4

12.3

B

ionic bonding, no free electrons

only able to conduct electricity when molten because ions can move

1

1

1

AO3

12.4

metallic

giant structure of atoms/ions arranged in regular pattern

electrons in the outer shell of metal atoms are delocalised and free to move throughout structure

giving rise to strong metallic bonds

1

1

1

1

AO1

4.2.1.5

13.1

55.6 × 5 = 278 mol

1

AO2

4.3.2.5

13.2

M_r = (6 × 12) + (12 × 1) + (6 × 16) = 180 g

concentration = 180 × 300

= 59 400 g/dm³

= 59.4 kg/dm³

1

1

1

1

AO1 × 2

AO2 × 2

4.3.2.1

4.3.2.5

13.3

award two marks for correct answer without working

allow 2970 g

1

1

AO2

4.3.2.5

14.1

heat the solution

until the water evaporates

leaving potassium chloride crystals

1

1

1

AO1

4.1.1.2

14.2

whole square filled with same-sized circle

circles arranged in regular pattern

all circles touching

1

1

1

AO1

4.2.2.1

14.3

potassium chloride has different properties as a compound to potassium and chlorine elements

allow named properties of K and Cl e.g., colour, electrical conductivities

1

AO1

4.1.1.2

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

zinc and copper chloride solution

1

AO2

4.4.1.2

01.2

hydrogen

1

AO1

4.1.2.5

01.3

less vigorously

1

AO1

4.1.2.5

01.4

lithium chloride

1

AO2

4.4.1.2

01.5

sodium > lithium > zinc > copper

one mark for one correct

two marks for two correct

three marks for all correct

3

AO2

4.4.1.2

02.1

reduced

loses

1

1

AO1

4.4.1.3

02.2

2Fe₂O₃ + 3C → 4Fe + 3CO₂

1

AO2

4.4.1.3

02.3

gold is unreactive

so it is found as elemental in the earth

1

1

AO1

4.4.1.3

03.1

steady bubbling from surface of zinc

or zinc gets smaller

or clear gas is formed

1

AO1

4.4.1.2

03.2

zinc chloride and hydrogen

1

AO2

4.4.1.2

03.3

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

one mark for formulae and state symbols of reactants & one mark for formulae and state symbols of reactants or one mark for correct formulae & one mark for state symbols

one mark for balancing

3

AO2

4.4.1.2

4.3.1.1

03.4

oxidised

as it loses electrons/forms positive ions

1

1

AO2

04.1

Mg or Al

does not react with CaCl₂, so is below Ca in the reactivity series.

reacts with copper sulfate and zinc chloride, so is above these two metals in the reactivity series.

1

1

1

AO2 × 2

AO3 × 1

4.4.1.2

04.2

X(s) + CuSO₄(aq) → Cu(s) + XSO₄(aq)

one mark for formulae and state symbols of reactants & one mark for formulae and state symbols of reactants or one mark for correct formulae & one mark for state symbols

one mark for balancing

3

AO2

4.4.1.2

4.3.1.1

04.3

test tube full of aluminium salt solution

add metal X

if no observation, then metal is aluminium

if displacement reaction occurs, metal is magnesium

1

1

1

1

AO2

4.4.1.2

05.1

1

1

1

1

AO2

4.4.1.3

05.2

2PbS(s) + 3O₂(g) → 2PbO(s) + 2SO₂(g)

one mark for formulae and state symbols of reactants & one mark for formulae and state symbols of reactants or one mark for correct formulae & one mark for state symbols

one mark for balancing

3

AO2

4.3.1.1

05.3

reduced

because oxygen is lost/electrons are gained

1

1

AO1

4.4.1.3

05.4

lead is below carbon in the reactivity series

but aluminium is above carbon in the reactivity series

1

1

AO1

4.4.1.3

05.5

one from:

• iron
• copper

1

AO1

4.4.1.3

06

Level 3: A detailed and coherent comparison is given, demonstrating a sound knowledge and understanding of displacement reactions in Halogens and metals.

5-6

AO1

4.4.1.2

4.1.2.6

Level 2: Correct descriptions of displacements are given for the Halogens and in metals. Some comparisons are made, but not all are clearly articulated.

3-4

Level 1: Some correct points are made about displacement reactions. Few comparisons are made, and these are not clearly articulated.

1-2

No relevant content

0

Indicative content

• in both the Halogen and metal reactions, a more reactive element displaces a less reactive element from a solution of its salt
• in both cases, one of the products is the less reactive Halogen or metal
• in both cases, the more reactive element ends up in a compound
• in the Halogen reaction, the more reactive Halogen is reduced (its atoms each gain one electron)
• in the metal reaction, the more reactive metal is oxidised (its atoms lose electrons)
• in the Halogen reaction, reactivity is based on tendency to form negative ions
• the closer the outer electron is to the nucleus, the more reactive the Halogen
• in the metal reaction, reactivity is based on the tendency to form positive ions

07.1

lithium

1

AO2

4.4.1.2

07.2

magnesium oxide

1

AO2

4.4.1.1

07.3

oxidised

magnesium has gained oxygen/lost electrons

1

1

AO1

AO2

4.4.1.1

07.4

magnesium is more reactive then carbon

therefore, carbon cannot displace magnesium from magnesium oxide

1

1

AO1

4.4.1.3

08.1

nickel reacts more vigorously than lead with HCl, so it is above lead in the reactivity series

nickel does not react with water, but iron does, so nickel is below iron in the reactivity series

nickel is between iron and lead in the reactivity series

1

1

1

AO3

4.4.1.2

08.2

add nickel to a solution such as iron chloride

there should be no reaction because nickel is less reactive than iron

add iron to a solution of nickel chloride

there should be a reaction because iron is more reactive than nickel

1

1

1

1

AO1

4.4.1.2

08.3

Ni + Cu²⁺ → Ni²⁺ + Cu

copper

one mark for reactants, one mark for products

2

1

AO2

4.4.1.4

09.1

do not mix a metal with a solution containing the same metal

allow suitable examples (e.g. do not mix magnesium with magnesium chloride solution)

1

AO3

4.4.1.2

09.2

copper

of the three metals in the experiment, it is the lowest in the reactivity series

or cannot displace any of the other metals

1

1

AO2

4.4.1.2

09.3

Mg(s) + Cu²⁺(aq) → Mg²⁺(aq) + Cu(s)

one mark for formulae and state symbols of reactants & one mark for formulae and state symbols of reactants or one mark for correct formulae & one mark for state symbols

one mark for balancing

3

AO2

4.4.1.4

09.4

before: 2,8,2

after: 2,8

1

1

AO2

4.4.1.7

09.5

reduces (potential harmful) waste after experiment

cheaper, as smaller amounts of metals and solutions are required

easier to observe on a white tile than in a test tube

1

1

1

AO3

10.1

there are no gaps/sticks between the nitrogen and hydrogen atoms

1

AO1

4.2.1.4

10.2

N atom should have 1 shell with 5 dots and 3 crosses. H atoms should have 1 shell with 1 dot and 1 cross each.

H atoms should each be sharing 1 dot and 1 cross.

2

AO1

4.2.1.4

10.3

the molecules do not have an overall electric charge/no charged particles that are free to move

1

AO3

4.2.2.1

10.4

gas

1

AO3

4.2.2.1

10.5

hydrazine has bigger molecules

and the intermolecular forces between bigger molecules are stronger

1

1

AO1

4.2.2.4

11.1

metal atoms lose outer shell/highest energy level electrons in their reactions

as atoms become bigger, their outer electrons are further from the nucleus (or more shielding)

so the electrostatic attraction between the nucleus and outer electrons gets weaker

so less energy is required to remove an electron

1

1

1

1

AO1 × 3

AO2 × 1

4.1.2.5

4.4.1.2

11.2

overall, radius decreases from top to bottom of the reactivity series

this indicates that the conclusion is true

calcium and magnesium do not fit the pattern, with both atoms being bigger than the one/two immediately above them in the reactivity series

this indicates that the conclusion is not entirely correct

overall, the trend identified in the conclusion is correct and the reason is correct

1

1

1

1

1

AO3

12.1

heat in a fume cupboard

avoid handling the lead/wash hands

2

AO2

12.2

lead and carbon dioxide

both products required for the mark

1

1

AO2

4.4.1.2

12.3

carbon dioxide has formed as a gas (and escaped from the evaporating basin)

1

AO1

4.3.1.3

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

1 – strong acid

5 – weak acid

9 – weak alkali

1

1

1

AO1

4.4.2.4

01.2

1 mol/dm³ solution of hydrochloric acid

1

AO2

4.4.2.4

01.3

hydrogen

H⁺

‘+’ must be superscript and on the right of the ‘H’ symbol

1

1

AO1

4.4.2.4

01.4

water

1

AO1

4.4.2.4

02.1

the H⁺ ion concentration in solution A is 10 times the H⁺ ion concentration in solution B

1

AO2

4.4.2.6

02.2

copper chloride, carbon dioxide and water

1

AO2

4.4.2.2

02.3

CuCl₂

1

AO2

4.4.2.2

03.1

pipette

1

AO1

4.4.2.5

03.2

two from:

• swirl the conical flask to ensure good mixing
• put it on a white tile so that you can see the colour
• add the solution slowly so that you know exactly when the end point has been reached

one mark for each correct answer

2

AO3

4.4.2.5

03.3

when she has obtained three concordant readings

‘concordant’ must be present for the mark to be awarded

1

AO1

4.4.2.5

03.4

1

AO2

4.4.2.5

03.5

number of moles of acid = concentration × volume in dm³ = 0.00 425 mol

one mole of NaOH reacts with one mole of HCl, so moles of NaOH = 0.00 425

allow error carried forward throughout

1

1

1

1

AO2

4.4.2.5

04.1

two from:

• stir/swirl the conical flask to ensure good mixing
• warm
• use (finer) powder of zinc oxide

one mark for each correct answer

2

AO3

4.4.2.3

04.2

stop when they see unreacted zinc oxide

1

AO1

4.4.2.3

04.3

to remove unreacted solid/zinc oxide

1

AO1

4.4.2.3

04.4

water bath and Bunsen burner or electric heater

1

AO1

4.4.2.3

04.5

evaporate only some of the water (until crystals start to form)

then remove the heat source and allow to crystallise from the solution at room temperature

1

1

AO3

4.4.2.3

04.6

ZnO(s) + 2HCl(aq) → ZnCl₂(aq) + H₂O(g)

1 mark for formulae and state symbols of reactants

1 mark for formulae and state symbols of products

or

1 mark for correct formulae

1 mark for correct state symbols

1 mark for balancing

3

AO2

4.4.2.2

4.3.1.1

04.7

from balanced equation, two moles of acid make one mole of zinc chloride

0.0 125 mol of acid makes 0.5 × 0.0 125 mol = 0.00 625 mole of zinc chloride

mass of one mole of zinc chloride = 65 + (35.5 × 2) = 136 g

maximum mass of zinc chloride

= number of moles × mass of one mole

= 0.00 625 × 136 g

= 0.85 g

1 mark for correct answer, 1 mark for correct number of significant figures

1

1

1

1

2

AO2

4.3.2.2

4.3.4

05.1

magnesium

because it loses electrons

Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g)

1 mark for formulae and state symbols of reactants

1 mark for formulae and state symbols of reactants

or

1 mark for correct formulae

1 mark for correct state symbols

1 mark for balancing

1

1

3

AO2

4.4.2.1

05.2

MgCl₂

H₂

1

1

AO2

4.4.2.1

06.1

weak – one from citric/ethanoic/carbonic

strong – one from hydrochloric/sulfuric/nitric

accept any correct acids

1

1

AO1

4.4.2.6

06.2

5

as pH decreases by one unit, H⁺ increases by a factor of 10

Here, H⁺ has decreased by a factor of 100, so pH increases by two units

AO1 × 1

AO2 × 2

4.4.2.6

06.3

H⁺ concentration in B is higher

B has the lower pH

1

1

1

1

AO2

4.4.2.6

07.1

2-

1

AO2

4.4.2.1

07.2

MgSO₄

1

AO2

4.4.2.1

07.3

MnCl₂

1

AO2

4.4.2.1

07.4

hydrogen

1

AO1

4.4.2.1

08.1

sulfuric acid

1

AO1

4.4.2.2

08.2

Level 3: The description of the method is detailed and accurate. Apparatus is named correctly, and the reasons given are clear and coherent.

5-6

AO1

4.4.2.3

Level 2: The descriptions of the method is correct, although lacks detail. Apparatus is named correctly, and reasons are given for some steps, although these may not be clearly explained.

3-4

Level 1: The method is outlined correctly. The names of one or two pieces of apparatus are given, as well as reasons for one or two steps only. The description overall lacks clarity and coherence.

1-2

No relevant content

0

Indicative content

• use a spatula to add excess copper hydroxide to the acid in a conical flask/beaker
• excess copper hydroxide is used so that all the acid reacts
• filter using filter paper and funnel to remove excess/unreacted copper hydroxide
• heat the filtrate in an evaporating basin over a water bath/with an electric heater until crystals begin to appear
• remove the heat and allow the rest of the water to evaporate slowly, to allow big crystals to form

allow correct diagrams, which should use standard representations of equipment, to aid description

08.3

Cu(OH)₂ + H₂SO₄ → CuSO₄ + 2H₂O

3

AO2

4.4.2.2

08.4

1

1

1

1

AO2

4.3.2.1

08.5

0.01 moles Cu(OH)₂ = 0.01 moles CuSO₄

M_r of CuSO₄ = 63.5 + 32 + (16 × 4) = 159.5

0.01 × 159.5

= 1.595g

= 1.6g

1

1

1

1

1

AO2

4.3.2.1

09.1

M_r of zinc nitrate = 189 g

from equation, one mol of zinc carbonate makes one mole of zinc nitrate

M_r of zinc carbonate = 125 g

mass = number of moles × M_r of ZnCO₃ = 0.05 × 125 g = 6.25 g

1

1

1

1

1

AO2

4.3.2.2

09.2

pH at start between one and three

pH increases as zinc carbonate added

because zinc carbonate neutralises the acid

1

1

1

AO1 × 1

AO2 × 2

4.4.2.4

10.1

pH probe

universal/broad range indicator

1

1

AO1

4.4.2.4

10.2

A

1

AO1

4.4.2.4

10.3

E

1

AO1

4.4.2.4

10.4

B

1

AO2

4.4.2.4

10.5

increases

1

AO2

4.4.2.4

11.1

2NaOH(aq) + H₂SO₄(aq) → Na₂SO₄ + 2H₂O

if NaSO₄ is used, but equation is still balanced, then maximum of 2 marks can be awarded

3

AO2

4.4.2.2

11.2

• measure set volume/named volume of sulfuric acid and place in conical flask
• using pipette
• add a suitable indicator to the conical flask
• put conical flask on a white tile
• fill burette with sodium hydroxide
• add sodium hydroxide 1cm³ at a time to the conical flask
• swirl after each addition
• when indicator changes colour, record the volume of sodium hydroxide (this is a rough titre)
• refill burette with sodium hydroxide solution
• set up new conical flask with same volume of sulfuric acid and indicator
• run sodium hydroxide into conical flask until near the end point
• swirling continuously
• add sodium hydroxide dropwise swirling after each addition
• until indicator changes colour
• record volume of sodium hydroxide added
• repeat until at least 3 concordant results are obtained

6

AO1

4.4.2.5

11.3

M_r of H₂SO₄ = 98

1

1

1

1

1

1

AO2

4.4.2.5

11.4

M_r of NaOH = 40

1

1

1

1

1

1

AO2

4.4.2.5

12.1

Z

1

AO3

4.4.2.6

12.2

W and Y

for a given concentration of solution, citric acid has the lower hydrogen ion, H⁺, concentration and higher pH

for the two solutions of concentration 0.1 mol/dm³, W has the higher pH

for the two solutions of concentration 1 mol/dm³, Y has the higher pH

1

1

1

1

AO3

4.4.2.6

12.3

a weak acid is partially dissociated in aqueous solution/a strong acid is fully dissociated in aqueous solution

1

AO1

4.1.2.6

12.4

strong – one from:

• sulfuric
• nitric

weak – one from:

• ethanoic
• carbonic

accept any correct acids

1

1

AO1

4.1.2.6

12.5

Level 3: Points that support and do not support the statement are made in detail, and a judgement made and justified. The answer is clearly and coherently written.

5-6

AO3

4.1.2.6

Level 2: Points that support and do not support the statement are made, but a judgement is not be included. The answer is reasonably clear, but not organised in a logical way.

3-4

Level 1: One or two relevant points are made. The answer is not clearly written nor is it logically organised.

1-2

No relevant content

0

Indicative content

• pH is a measure of the hydrogen ion concentration
• the greater the hydrogen ion concentration, the lower the pH
• for weak and strong acids of the same concentration, the hydrogen ion concentration is always smaller in the weak acid, so the pH is always higher
• so the statement is true for solutions of the same concentration
• but a dilute solution of a strong acid could have a smaller hydrogen ion concentration than a more concentrated solution of a weak acid
• so the statement is not always true for solutions of different concentrations

13.1

Noble Gases

1

AO1

4.1.2.4

13.2

2,8,8

1

AO2

4.1.1.7

13.3

they have stable arrangements of electrons/full outer shell

1

AO1

4.1.2.4

13.4

increases

1

AO2

4.1.1.5

14.1

31

1

AO2

4.1.1.5

14.2

69 – 31 = 38

1

AO2

4.1.1.5

14.3

31 – 3 = 28

1

AO2

4.1.1.5

14.4

one from:

• boron
• aluminium
• indium
• thallium

1

AO2

4.1.2.1

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

hydrogen

1

AO2

4.4.3.4

01.2

2Cl⁻ (aq) → Cl₂(g) + 2e⁻

one mark for formulae and state symbols of reactants

one mark for formulae and state symbols of reactants

or

one mark for correct formulae

one mark for correct state symbols

one mark for balancing

3

AO2

4.4.3.5

01.3

independent – concentration of sodium chloride solution

dependent – current

1

1

AO2

01.4

distance between electrodes or size of electrodes or volume of solutions

1

AO3

01.5

Graph of ‘concentration of sodium chloride solution in g/dm³’ (horizontal axis) against ‘current in amps’ (vertical axis)

Points plotted at (0.2,0.2), (0.4,0.33), (0.6,0.43), (0.8, 0.47), (1.0, 0.52)

one mark for plotting three points

one mark for plotting all points

one mark for line of best fit

3

AO2

AO3

01.6

as concentration increases, the current also increases

as concentration increases, more ions are present to carry the charge

1

1

AO3

4.4.3.1

02.1

cathode/negative

1

AO1

4.4.3.1

02.2

chlorine zinc

1

AO2

4.4.3.2

02.3

in solid zinc, chloride ions are not free to move

so cannot conduct electricity

and move to the electrodes

1

1

1

AO1

4.4.3.1

02.4

ZnCl₂(l) → Zn(s) + Cl₂(g)

1

AO1

4.4.2.2

03.1

too reactive to extract by reduction (with carbon)/reacts with carbon

1

AO1

4.4.3.3

03.2

cathode/negative

1

AO1

4.4.3.2

03.3

lots of energy needed to melt potassium sulfate

2

AO3

4.4.3.3

03.4

cathode: 2H⁺(aq) + 2e^– → H₂(g)

anode: 4OH⁻(aq) → O₂(g) + 2H₂O(l) + 4e⁻

6

AO2

4.4.3.3

03.5

potassium metal is not produced in the electrolysis of potassium

solution of potassium would react with the water/is too reactive

1

AO3

4.4.3.3

04.1

aluminium is above carbon in the reactivity series

1

AO1

4.4.3.3

04.2

carbon/graphite

1

AO1

4.4.3.3

04.3

carbon reacts with oxygen produced at the anode, forming carbon dioxide which burns away the anode

1

AO1

4.4.3.3

04.4

(liquid) aluminium oxide

and cryolite

accept ‘bauxite’ instead of ‘(liquid) aluminium oxide’

1

1

AO1

4.4.3.3

04.5

Al³⁺(aq) + 3e⁻ → Al(l)

one mark for formulae and state symbols of reactants

one mark for formulae and state symbols of reactants

or

one mark for correct formulae

one mark for correct state symbols

one mark for balancing

3

AO2

4.4.3.5

04.6

large amounts of energy are required for the electrolysis/to keep the aluminium liquid

1

AO1

4.4.3.3

05.1

unreactive/does not react

conductor that carries an electric current into a liquid or solution

1

1

AO1

4.4.3.1

05.2

PbBr₂

1

AO2

4.2.1.2

05.3

Level 3: The description, explanation and names of the products are correct. The account is clearly written and well-structured.

5-6

AO1

4.4.3.1

4.4.3.5

Level 2: The description, explanation and names of the products are mainly correct, although there might be one or two errors. The account is written fairly clearly, but is somewhat disorganised.

3-4

Level 1: The description, explanation and names of products are partly correct, but there are several errors and the account lacks detail. The account is not written clearly, and consists of isolated facts rather than one flowing piece of work.

1-2

No relevant content.

0

Indicative content

• the current causes the ions to move to the electrodes
• positive lead ions move to the negative electrode/cathode
• negative bromide ions move to the positive electrode/anode
• at the positive electrode, positive lead ions gain electrons, so lead atoms are formed
• at the negative electrode, negative bromide ions lose electrons, so bromine is formed
• cathode: Pb²⁺ + 2e^– → Pb
• anode: 2Br^– → 2e^– + Br₂

06.1

higher temperatures are required to melt the salts

1

AO3

06.2

to collect any gases given off at the electrodes

1

AO1

4.4.3.4

06.3

the cathode will become pink-brown

1

AO2

4.4.3.4

06.4

if lit splint goes out with a squeaky pop, then the gas is hydrogen/H₂

if glowing splint relights, then the gas is oxygen/O₂

1

1

AO1

4.4.3.4

06.5

some water molecules break down to make hydrogen ions and hydroxide ions

the hydrogen ions are attracted to the cathode

where they gain electrons, as shown in the half equation below

2H⁺(aq) + 2e⁻ → H₂(g)

1

1

3

AO1

4.4.3.4

4.4.3.5

07.1

row one: does not conduct because ions not free to move

row two: positive sodium ions move to the negative electrode, where they pick up electrons to make sodium metal

negative chloride ions move to the positive electrode, where they donate electrons to make chlorine gas

1

1

1

AO2

4.2.2.3

07.2

2H⁺ (aq) + 2e⁻ → H₂(g)

one mark for formulae and state symbols of reactants

one mark for formulae and state symbols of reactants

or

one mark for correct formulae

one mark for correct state symbols

one mark for balancing

3

AO2

4.4.3.5

07.3

Level 3: The explanation is correct. The account is clearly written and well-structured.

5-6

AO2 × 3

AO3 × 3

4.4.3.4

Level 2: The explanation is mainly correct. The account is written fairly clearly, but is somewhat disorganised.

3-4

Level 1: The explanation is partly correct, but there are several errors and the account lacks detail and clarity.

1-2

No relevant content

0

Indicative content

• in the solution, water molecules break down producing hydrogen ions and hydroxide ions
• sodium and chloride ions are also present in the solution
• the current causes the ions to move to the electrodes
• positive sodium and hydrogen ions move to the negative electrode/cathode
• negative chloride and hydroxide ions move to the positive electrode/anode
• at the positive electrode, positive hydrogen ions gain electrons, so hydrogen is formed
• hydrogen gas makes a lit splint give a squeaky pop
• at the negative electrode, hydroxide ions react to make oxygen gas
• oxygen gas relights a glowing splint
• both chlorine and oxygen are formed because of the relatively low concentration of chloride ions in the dilute solution
• also, at the negative electrode, chloride ions react to make chlorine gas, which has a characteristic smell

08.1

too reactive/reacts with carbon/more reactive than carbon

1

AO1

4.4.3.3

08.2

carbon/graphite

1

AO1

4.4.3.3

08.3

aluminium oxide must be molten for electrolysis to take place

cryolite reduced the melting point of the mixture

therefore, reducing the cost of the electrolysis

1

1

1

AO1

AO2

4.3.3.3

08.4

aluminium ions have a positive charge

so they are attracted to the negatively charged cathode

1

1