Oxford Revise AQA GCSE Chemistry | Chapter C15 answers

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

propane

1

AO2

4.7.1.1

01.2

ethanol

1

AO2

4.7.2.3

01.3

all points plotted properly

line of best fit

1

1

AO2

AO3

4.7.2.4

01.4

for each homologous series, boiling point increases with number of carbon atoms

for each number of carbon atoms, the boiling point increases from alkane to alcohol to carboxylic acid

1

1

AO3

01.5

as molecular size increases, strength of intermolecular forces increases

so more energy is needed to overcome the forces

1

1

AO2

4.2.2.4

02.1

ethene is drawn with 2 C atoms and 4 H atoms. The C atoms are linked together by an ‘=’ and each C atom is joined to 2 H atoms by a ‘-‘

ethanol is drawn with 2 C atoms, 5 H atoms and 1 O atoms. One carbon atoms is joined to 1 C atom and 3 atoms by ‘-‘. The other C atom is joined to 1 C atom, 2 H atoms and 1 atoms by ‘-‘. The O atom is joined to 1 C atom and 1 H atom by ‘-‘

butane is drawn with 4 C atoms and 10 H atoms. 2 C atoms are joined to 3 H atoms and 1 C atom by ‘-‘. 2 C atoms are joined to 2 C atoms and 2 H atoms.

butanol is drawn with 4 C atoms, 10 H atoms and 1 O atom. One C atom is joined to 3 H atoms and 1 C atom by a ‘-‘. Two C atoms are joined to 2 C atoms and 2 H atoms by a ‘-‘. One C atom is joined to 1 C atom, 2 H atoms and 1 O atom by ‘-‘. One O atom is joined to 1 C atom and 1 H atom.

1

1

1

1

AO1

4.7.2.1

4.7.2.3

02.2

carboxylic acid

1

AO1

4.7.2.4

02.3

butene

1

AO1

4.7.2.1

03.1

bubbles

because carbon dioxide gas is made (in the chemical reaction)

1

1

AO1

4.7.2.4

03.2

to speed up the reaction

1

AO1

4.6.1.4

03.3

ethyl ethanoate

1

AO1

4.7.2.4

03.4

(sweet) smell

1

AO1

4.7.2.4

04.1

colour change from orange-brown to colourless

1

AO1

4.7.2.2

04.2

3 C atoms, 6 H atoms and 2 Br atoms are drawn.

one C atom is joined to 3 H atoms and 1 C atom by -.

one C atom is joined to 2 C atoms, 1 H atom and 1 Br atom by -.

one C atom is joined to 1 C atom, 2 H atoms and 1 Br atom by -.

1

AO2

4.7.2.2

04.3

60 °C

metal catalyst

1

AO1

4.7.2.2

04.4

3 C atoms and 8 H atoms are drawn.

2 C atoms are joined to 3 H atoms and 1 C atom by –

1 C atom is joined to 2 C atoms and 2 H atoms by –

1

1

AO2

4.7.1.1

4.7.2.2

05.1

as number of chlorine atoms increases, pH decreases

showing that the hydrogen ion concentration increases

showing that the degree of ionisation must be greater

1

1

1

AO2

4.4.2.6

05.2

bubbles formed in both cases

D bubbles more vigorously/C bubbles less vigorously

1

1

AO3

4.4.2.6

4.7.2.4

05.3

calcium propanoate

1

AO3

4.7.2.4

06.1

Level 3: The identities of X, Y and Z are given correctly. The justification draws on all the available evidence and is detailed, logical and coherent.

5-6

AO3

4.7.2.2

4.7.2.3

4.7.2.4

Level 2: The identities of two of X, Y and Z are given correctly. Some points, drawing on the evidence, are made to justify their identities.

3-4

Level 1: The identities of one of X, Y and Z are given correctly. Some points are made to justify this conclusion, but they are not clearly articulated and the structure of the answer is disorganised.

1-2

No relevant content.

0

Indicative content

• Z bubbles with sodium carbonate, so Z is ethanoic acid
• Z bubbles more quickly with sodium than X, so Z is ethanoic acid
• X reacts with sodium more slowly than Z, so is ethanol
• X burns with a blue flame, so is ethanol
• Y does not react with sodium or sodium carbonate, so Y is pentene
• Y burns with a smoky flame, so is pentene

06.2

alcohols

1

AO3

4.7.2.3

06.3

propanoic acid

1

AO2

4.7.2.4

07.1

the alcohol

1

AO2

07.2

two from:

• volume/mass of water
• distance between the lamp and the container
• volume/mass/amount of alcohol burnt

allow other suitable answers

award one mark for each correct control variable, to a maximum of two

2

AO2

07.3

as size of alcohol increases, temperature increase of the water increases

because more carbon atoms in the alcohol/more bonds are broken

therefore, more energy is transferred in the exothermic reaction to the water

1

1

1

AO3

4.5.1.3

07.4

C₄H₉OH + 6O₂ → 4CO₂ + 5H₂O

one mark for formulae of reactants

one mark for formulae of products

one mark for balancing

3

AO2

4.7.2.3

07.5

5 C atoms, 12 H atoms and 1 O atom.

one C atom is joined to 3 H atoms and 1 C atom.

3 C atoms are joined to 2 C atoms and 2 H atoms.

one C atom is joined to 1 C atom, 2 H atoms and 1 O atom

O atom is joined to 1 C atom and 1 H atom

1

AO3

4.7.2.3

08.1

yeast

1

AO1

4.7.2.3

08.2

37 °C

allow any value between 30 °C and 40 °C

1

AO1

4.7.2.3

08.3

alcoholic drinks

fuel

1

1

AO1

4.7.2.3

08.4

M_r of ethanol = (2 × 12) + (6 × 1) + 16 = 46

M_r of glucose = (6 × 12) + (12 × 1) + (6 × 16) = 180

mass of 0.87 mol of glucose = 0.87 × 180 = 156.6 g

1

1

1

1

1

AO2

4.3.2.1

4.3.2.2

09.1

M_r of C₁₀H₂₁OH = (10 × 12) + (22 × 1) + 16

= 158

award two marks if correct answer given with no working

1

1

AO2

4.3.1.2

09.2

X

1

AO2

4.7.2.2

09.3

C₁₀H₂₂

1

AO2

4.7.2.2

09.4

ester

1

AO2

4.7.2.4

10.1

butane

1

AO1

4.7.1.1

10.2

propene

1

AO1

4.7.2.2

10.3

C₈H₁₆

1

AO2

4.7.2.1

10.4

C₅H₁₂

1

AO2

4.7.1.1

11.1

methanol

1

AO1

4.7.2.3

11.2

as the number of carbon atoms increases,

the solubility in water decreases

1

1

AO2

11.3

the hydrocarbon part of the molecule does not mix with the water

1

AO3

4.7.2.3

11.4

C₅H₁₁OH

mass of one mole = (5 × 12) + (12 × 1) + 16 = 88 g

so concentration = 0.030 × 10 = 0.30 mol/dm³

one mark for correct answer, one mark for two significant figures

1

1

1

2

AO2

4.3.4

12.1

neutralisation

1

AO1

4.4.2.2

12.2

no

energy is not created or destroyed in a chemical reaction

the test tube got hotter because energy was transferred from the reaction/chemicals/bonds to the surroundings

1

1

1

AO2

4.5.1.1

12.3

energy transferred from the surroundings to the system to break bonds in the reactants

energy transferred to the surroundings on the formation of the bonds in the products

more energy released (on formation of bonds) then transferred (to break bonds).

1

1

1

AO2

4.5.1.3

12.4

one from:

• combustion
• oxidation

allow other valid examples (e.g., respiration)

1

AO1

4.5.1.1

13.1

M_r = 40 + 12 + (3 × 16)

= 100

2

AO2

4.3.2.1

13.2

1

1

AO1

4.3.2.1

13.3

CaO

1

AO1

4.1.1.1

13.4

M_r of CaO = 40 + 16 = 56

M_r of CO₂ = 12 + 16 × 2 = 44

atom economy =

1

1

1

1

AO2

4.3.3.2

13.5

gas produced

lost from reaction vessel

1

1

AO1

4.3.1.1