The questions are on the alcohols and carboxylic acids test. Take it under real conditions before reading the mark scheme.
Quick answer: Alcohols contain –OH and carboxylic acids contain –COOH. This mark scheme gives the model answers and the marks for the 8 questions of the Chemistry 9-10 test on alcohols and carboxylic acids, from functional groups to plastic waste, with the equivalent answers to accept.
Use this guide to mark your paper out of 20. Give the marks for correct formulae, balanced equations and clear explanation. Accept any other correct wording and either British or American spelling.
Level: Chemistry grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: GCSE C7
Question 2 Fermentation conditions (3 marks)
a. C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂.b. Above 60 °C the enzymes in the yeast are denatured and fermentation stops.
Marking: a. 1 mark for correct formulae, 1 for balancing. b. 1 mark for denatured enzymes.
Question 3 Making an ester (3 marks)
a. Propyl ethanoate.b. Water.
c. Concentrated sulfuric acid.
Marking: 1 mark each.
Question 4 Glucose calculation (3 marks)
a. n = 18 ÷ 180 = 0.10 mol.b. Ethanol = 0.20 mol × 46 = 9.2 g.
c. CO₂ = 0.20 mol × 44 = 8.8 g.
Marking: 1 mark each. Check: 9.2 + 8.8 = 18.0 g.
Question 5 Addition polymer (3 marks)
a. Addition polymerisation.b. –CH₂–CH(CH₃)–.
c. It does not, because the C=C bonds have been used up in forming the chain.
Marking: 1 mark each.
Question 6 Condensation polymer (3 marks)
a. The ester link.b. Water.
c. Condensation polymerisation needs two functional groups per monomer and loses a small molecule; addition polymerisation uses a C=C bond and loses nothing.
Marking: 1 mark each.
Question 7 Weak acid (2 marks)
A weak acid ionises only partially in water. With sodium carbonate it fizzes because carbon dioxide gas is released.Marking: 1 mark for partial ionisation, 1 mark for fizzing and CO₂.
Question 8 Plastic waste (1 mark)
They are unreactive and not biodegradable, so they stay in the environment for a very long time.Marking: 1 mark.
