Oxford Revise AQA GCSE Chemistry | Chapter C5 answers

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