Oxford Revise AQA GCSE Chemistry | Chapter C19 answers

C19: Using the Earth's resources

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Answers

Extra information

Mark

AO / Specification reference

01.1

water that is safe to drink

1

AO1

4.10.1.2

01.2

passing water through filter beds – to remove pieces of solid

sterilising – to kill microorganisms

desalination – to remove dissolved salts

award one mark for one or two correct; award two marks for all three correct

2

AO1

4.10.1.2

01.3

two from:

  • chlorine
  • ozone
  • ultraviolet light

one mark for each correct answer up to two marks

2

AO1

4.10.1.2

01.4

advantage – water can be obtained from seawater if supplies of freshwater are limited

disadvantage – large amount of energy required

1

1

AO1

4.10.1.2

02.1

crushing and melting the jar to make a bottle

1

4.10.2.2

02.2

SiO2

CaCO3

sodium carbonate

1

1

1

AO2

4.1.1.1

02.3

reduced use of raw materials

reduced use of energy

reduced waste

1

1

1

AO1

4.10.2.2

03.1

use a pipette instead of a measuring cylinder

to measure the volume of water more accurately

1

1

AO3

4.10.1.2

03.2

heat until some of water has evaporated, then leave in a dry place for the rest of the water to evaporate

evaporating basin less likely to break

1

1

AO3

4.10.1.2

03.3

wear eye protection

do not touch hot apparatus

1

1

AO3

4.10.1.2

03.4

A

1

AO3

4.10.1.2

03.5

C

greater mass of dissolved solids

1

1

AO3

4.10.1.2

04.1

Bunsen burner reaches high enough temperature (to make the water boil) (water bath does not)

1

AO2

4.10.1.2

04.2

so that there are no gaps between the test tube and the cooling system

1

AO3

4.10.1.2

04.3

no bung in the top of the flask

1

AO3

4.10.1.2

04.4

pure water leaves the seawater as steam

so concentration of salt increases

1

1

AO2

4.10.1.2

05.1

grow plants on the low-grade ore

harvest and burn the plants

add sulfuric acid to the ash

displace copper from the copper sulfate solution by adding scrap iron/use electrolysis

1

1

1

1

AO1

4.10.1.4

05.2

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

5-6

AO1 × 3

AO3 × 3

4.10.1.4

4.10.2.2

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

  • scrap copper advantages
    • uses copper waste, preventing its need to be disposed of in other ways

  • scrap copper disadvantages
    • cannot be obtained from mixtures containing very small amounts of copper

    • copper must be separated from other materials it is mixed with

  • bioleaching advantages
    • copper can be obtained from lower-grade ores

  • bioleaching advantages
    • slow

05.3

\(
\frac{{22.1}}{{100}} \times m = 50{\rm{\ kg\ where\ }}m{\rm{\ is\ the\ mass\ of\ ore\ mined}}
\)

m = 226 kg

waste = 226 – 50

= 176 kg

1

1

1

1

AO2

4.10.1.1

06.1

Level 3: The comparisons are detailed and accurate. The writing is clear, coherent and logical and comparisons are clearly made. A conclusion about which is better is clearly made and justified in detail.

5-6

AO3

4.10.2.1

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. A conclusion about which is better is given, but not justified.

3-4

Level 1: Some comparisons are correct. The writing lacks clarity, coherence and logic, and the comparisons are not clearly expressed. No conclusion is given about which is better.

1-2

No relevant content

0

Indicative content:

  • PLA advantages
    • lower energy requirements

    • smaller amounts of greenhouse gases produced

    • biodegradable

  • PLA disadvantages
    • requires more land

    • pollutes soil more

    • not recyclable

  • PET advantages
    • requires less land

    • pollutes soil less

    • recyclable

  • PET disadvantages
    • higher energy requirements

    • greater amounts of greenhouse gases produced

    • not biodegradable

06.2

\(
\begin{array}{l}
\frac{0.0565}{12}\\
= 0.0047083\\
= 4.71 \times 10^{-3}\rm{\ m}^2
\end{array}
\)

1

1

1

AO2

06.3

energy required lower for recycled PET

one from:

  • raw materials/oil does not need to be sources
  • reshaping PET required less energy than making PET from raw materials
  • shorter process
  • less transportation costs as recycling can be carried out locally/raw materials don’t have to be transported

accept any sensible answer

1

1

AO3

4.10.2.1

07.1

2,3,4

all three required for the mark

1

AO3

4.10.2.1

07.2

extracting and processing raw materials: 1

manufacturing and packaging: 2/3/4

use and operation during its lifetime: 6

disposal at the end of life: 7

1

1

1

1

AO1

AO3

4.10.2.1

07.3

energy to heat water used for washing

1

AO3

4.10.2.1

07.4

recycle/give to someone else/use for rags

1

AO3

4.10.2.2

08.1

organic matter

harmful microbes

1

1

AO1

4.10.1.3

08.2

screening and grit removal

sedimentation to make sewage sludge and effluent

anaerobic digestion of sludge

aerobic biological treatment of effluent

1

1

1

1

AO1

4.10.1.3

08.3

groundwater has smaller amounts of impurities in it/groundwater contains less organic matter and harmful microbes

1

AO1

4.10.1.3

09.1

760

allow any answer between 755 and 765

1

AO2

4.10.1.3

09.2

\(
\begin{array}{l}
\frac{{45}}{{760}} \times 100\\
= 6\%
\end{array}
\)

1

1

AO2

4.10.1.1

09.3

\(
\begin{array}{l}
\rm{mass\ of\ T}\rm{a}_2\rm{O}_5 = \frac{{80}}{{100}} \times 72 = 57.6{\rm{\ kg}}\\
{\rm{mass\ of\ Ta\ in\ }}57.6{\rm{\ kg\ of\ T}}{{\rm{a}}_2}{{\rm{O}}_5} = \\
\frac{{(2 \times 181)}}{{(2 \times 181) + (5 \times 16)}}\\
\times 57.6\\
= 47{\rm{\ kg}}
\end{array}
\)

1

1

1

AO2

4.10.1.1

09.4

\(
\begin{array}{l}
\frac{{1.5 \times {{10}^5}}}{{760}}\\
= 197
\end{array}
\)

accept 200

1

1

AO2

4.10.1.1

09.5

two from:

  • more tantalum ore might have been found
  • less tantalum might have been extracted each year
  • new technology might enable tantalum to be extracted from ores from which it was not previously economic to extract the metal
  • demand for tantalum may increase/decrease
  • more tantalum recycled

one mark for each correct answer up to two marks

2

AO3

4.10.1.1

10.1

development that meets the needs of current generations without compromising the ability of future generations to meet their own needs

1

AO1

4.10.1.1

10.2

wood is renewable

wood is biodegradable

1

1

AO3

4.10.1.1

10.3

less land is required for plastic production

1

AO3

4.10.1.1

11.1

alkanes

1

AO1

4.7.1.1

11.2

C9H20

1

AO2

4.7.1.1

11.3

butane

1

AO1

4.7.1.1

11.4

no change/remain orange

1

AO2

4.7.1.3

11.5

C4H10(g) + 6.5O2(g) → 4CO2(g) + 6H2O(g)

3

AO2

4.7.1.3

11.6

temperature of 550°C

catalyst

1

1

AO1

11.7

1 C atom and 4 H atoms are drawn

each H atom shares 1 dot and 1 cross with C atom

2

AO1

4.2.1.4

11.8

shorter-wave radiation from the Sun penetrates the atmosphere

the Earth’s surface emits longer-wavelength radiation

greenhouse gases absorb some of the longer-wavelength radiation

so trapping some of the radiation within the atmosphere

1

1

1

1

AO1

4.9.2.1

12.1

bubbling through limewater

1

AO1

4.8.2.3

12.2

sulfate

1

AO2

4.8.3.5

12.3

mixture of metals/metal does not produce result in flame test

1

AO2

4.8.3.1

12.4

three from:

  • more accurate
  • more sensitive
  • can detect multiple metal ions
  • can measure concentrations of ions

one mark for each correct answer up to three marks

do not accept more rapid

1

1

1

1

1

AO1

4.8.3.6

4.8.3.7

12.5

zinc

lithium

1

1

AO3

4.8.3.7

13.1

12 C atoms, 2 N atoms, 2 O atoms and 2 H atoms are drawn

one C atom is joined to 1 O atom by = and is joined to a C atom by –one 8 C atoms are joined to 2 C atoms by –

one C atom is joined to 1 C atom and 1 N atom by – and joined to a C atom by =

2 N atoms are joined to 2 C atoms and 1 H atom by –

one C atom is joined to 1 N atom and 1 C atom by –

all atoms are inside square brackets with a – extending outside the brackets

subscript n to the right of the bracket

2

AO2

4.7.3.2

13.2

condensation (polymerisation)

1

AO2

4.7.3.2

13.3

HCl/hydrogen chloride

1

AO2

4.7.3.2

14.1

carbon dioxide

1

AO1

4.9.1.2

14.2

water vapour/methane/ammonia

1

AO1

4.9.1.2

14.3

carbon dioxide

1

AO1

4.9.2.1

14.4

no

some greenhouse gases in the atmosphere are needed to maintain the temperatures that support life on Earth

1

1

AO1

4.9.2.1

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