Oxford Revise AQA GCSE Combined Science Foundation | Chapter C12 answers

C12: Chemical analysis

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

mixed

temperatures

pure

answers must be in this order

1

1

1

AO1

5.8.1.1

01.2

thermometers or data logger

1

AO1

5.8.1.1

01.3

A

1

AO2

5.8.1.1

01.4

carbon dioxide gas

1

AO1

5.8.1.1

01.5

a formulation is a mixture that has been designed as a useful product

1

AO1

5.8.1.2

01.6

any one example from these categories: fuels, cleaning agents, paints, medicines, alloys, fertiliser and foods

1

AO1

5.8.1.2

02.1

98 °C

exact answer only

1

AO2

5.2.2.1

02.2

range of boiling points

pure substances have a specific boiling point

1

1

AO2

5.8.1.1

02.3

98 – 103 °C

1

AO3

5.8.1.1

02.4

in everyday language, pure means it has had nothing added to it/is in its natural state

but in science it means a substance with only one element or compound

orange juice is made up of multiple substances, so is not scientifically pure

1

1

1

AO1

5.8.1.1

03.1

a mixture that has been designed as a useful product

1

AO1

4.8.1.2

03.2

\(
\begin{align}
& \frac{20}{20 + 70 + 110} \times 100\%\ \textbf{or}\ \frac{20}{200} \times 100\% \\
& = 10%
\end{align}
\)

award two marks if answer correct and no working shown

1

1

AO2

4.8.1.2

03.3

C7H16

1

AO2

4.7.1.1

03.4

ethanol is renewable/can be obtained sustainably/burns more cleanly

1

AO1

4.10.1.1

04.1

filtration

1

AO2

5.1.1.2

5.8.1.3

04.2

distillation

1

AO2

5.1.1.2

5.8.1.3

04.3

chromatography

1

AO2

5.1.1.2

5.8.1.3

04.4

filtration

1

AO2

5.1.1.2

5.8.1.3

05.1

magnesium chloride

hydrogen

accept answers in either order

1

1

AO2

5.4.2.1

05.2

hold a lit splint at the end of the test tube of gas

pop sound

1

1

AO1

5.8.2.1

05.3

bubble through limewater

turns cloudy

1

1

AO1

5.8.2.3

05.4

chlorine

1

AO2

5.8.2.4

06.1

formulation

1

AO1

5.8.1.2

06.2

(6 + 3 + 1 = 10)

\(
\begin{align}
& \frac{1}{10} \times 100\\
& = 10%
\end{align}
\)

accept 10% for two marks

1

1

AO2

5.8.1.2

06.3

\(
\begin{align}
& \frac{6}{10} = 0.6 \\
& 250 \times 0.6 = 150\ \textrm{cm}^3
\end{align}
\)

1

1

AO2

5.8.1.2

07.1

A matching diagram that connects gases to their identifying reactions. Hydrogen is mapped to burns with a squeaky pop. Oxygen is mapped to relights a glowing splint. Chlorine is mapped to bleaches damp litmus paper.

3

AO1

5.8.2.1

5.8.2.2

5.8.2.4

07.2

(g) + (aq) → (s) + (l)

1

AO2

5.8.2.3

08.2

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

5-6

AO1

5.8.1.3

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

3-4

Level 1: Some correct points but lacks detail. The writing lacks clarity, coherence and logic.

1-2

No relevant content.

0

Indicative content

  • chromatography
  • draw line in pencil onto paper
  • onto pencil line spot the ink
  • in a small beaker, add solvent/water
  • wrap paper around a pencil/stirring rod
  • balance pencil/stirring rod so that bottom of paper dips into solvent.
  • make sure solvent is below pencil line
  • leave until solvent has travelled to the top of the paper
  • remove from beaker

08.2

A piece of paper with an origin line drawn

3 dots spaced vertically and in line

three spots drawn in a vertical line

accept any vertical spacing between the spots

dot on pencil line is not required

1

AO2

5.8.1.3

08.3

\(
\rm{Value\ larger\ than\ } \frac{1}{\rm{Rf}}\ \rm{values\ are\ always\ less\ than\ }1
\)

1

AO3

5.8.1.3

08.4

red dye

1

AO3

5.8.1.3

08.5

one from:

  • one of the substances is made of two chemicals
  • impurity in the student’s ink sample

accept other relevant experimental errors

a specific experimental error must be given, do not award mark for “student made an error”

1

AO3

5.8.1.3

08.6

to avoid bias/cheating

1

AO3

5.8.1.3

09.1

A: carbon dioxide

B: oxygen

C: hydrogen

1

1

1

AO2

4.8.2.1

4.8.2.2

4.8.2.3

09.2

damp litmus paper

bleached

1

1

AO1

4.8.2.4

10.1

\(
\frac{1.0}{3.3} = \frac{0}{3}
\)

+/- 0.05

2

AO2

5.8.1.3

10.2

pure

only one spot

1

1

AO2

5.8.1.3

10.3

spot drawn anywhere between spots for A and B

1

AO2

5.8.1.3

11.1

anode: oxygen

cathode: copper

1

1

AO2

5.4.3.4

11.2

glowing splint

relights

1

1

AO1

5.8.2.2

11.3

chlorine

1

AO2

5.4.3.2

11.4

damp litmus paper

bleached/turns white

1

1

AO1

5.8.2.4

11.5

hydrogen

1

AO1

5.1.2.5

11.6

burning split

pop

1

1

AO1

5.8.2.1

12.1

filtration

1

AO1

5.1.1.2

12.2

Level 3 (5-6 marks): A full description of the method provided, with at least two pieces of equipment named.

5-6

AO1

5.1.1.2

Level 2 (3-4 marks): 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 (1-2 marks): Method identifies idea that water needs to evaporate/be heated. No equipment named.

1-2

No relevant content.

0

Indicative content:

method:

  • 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

12.3

chromatography

1

AO1

5.1.1.2

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