Question 1Multiple choice · 1 mark
Which compound is shown?
- A propane
- B propene
- C butanoic acid
- D propanoic acid
Show answer
Answer: D
Free Alcohols & carboxylic acids questions for IGCSE Chemistry (0620), part of Organic chemistry. Each question has the answer and the marking points an examiner would look for.
Generate a full Alcohols & Carboxylic Acids worksheet →All Organic chemistry questionsWhich compound is shown?
Answer: D
An alkane, C12H26, is cracked to form an alkane with 8 carbon atoms and ethene only.
How many molecules of ethene are formed from one molecule of C12H26?
Answer: B
Esters have fruity smells.
Name the ester formed from methanol and propanoic acid.
State one use of esters.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | methyl propanoate methyl propanoate B1 | 1 |
| (b) | flavourings; perfumes; solvents flavourings / perfumes / solvents B1 | 1 |
Ethanol can be made by fermentation or from ethene.
Describe the conditions for fermentation.
Give one advantage and one disadvantage of fermentation compared with hydration of ethene.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | yeast, 25–35 °C, no oxygen glucose solution with yeast B1 warm (about 25–35 °C) B1 absence of oxygen (anaerobic) B1 | 3 |
| (b) | renewable; slow / impure advantage: uses renewable resources / low temperature B1 disadvantage: slow / batch process / impure ethanol B1 | 2 |
This question is about alcohols and carboxylic acids.
Ethanol can be made by the fermentation of glucose.
Write the equation for the fermentation of glucose, C₆H₁₂O₆.
State two conditions needed for fermentation.
Calculate the maximum mass of ethanol made from 90 g of glucose. [Mᵣ: glucose, 180; ethanol, 46]
Explain why fermentation stops when the ethanol concentration reaches about 15%.
Ethanol is oxidised to ethanoic acid by acidified potassium manganate(VII). State the colour change and the type of reaction.
Methanoic acid reacts with ethanol in the presence of an acid catalyst. Name the ester formed and give its structural formula.
Ethanoic acid reacts with sodium carbonate. Write the equation and describe what is seen.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a)(i) | C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ C₂H₅OH and CO₂ as products B1 balanced B1 | 2 |
| (ii) | yeast; about 30 °C; absence of oxygen Any 2 of: yeast; 25–35 °C; absence of oxygen / anaerobic; aqueous solution B2 | 2 |
| (iii) | 46.0 g moles glucose = 0.500, moles ethanol = 1.00 M1 46.0 g A1 | 2 |
| (iv) | yeast is killed by the ethanol the ethanol kills / denatures the yeast (enzymes) B1 | 1 |
| (b) | purple to colourless; oxidation purple to colourless B1 oxidation B1 | 2 |
| (c) | ethyl methanoate, HCOOC₂H₅ ethyl methanoate B1 HCOOC₂H₅ B1 | 2 |
| (d) | 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂; fizzing correct products CH₃COONa, H₂O, CO₂ B1 balanced B1 effervescence / fizzing / solid dissolves B1 | 3 |
Ethanol is used as a fuel and a solvent.
Write a balanced equation for the complete combustion of ethanol.
Give one use of ethanol other than as a fuel.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O correct formulae B1 balanced B1 | 2 |
| (b) | solvent; drinks; disinfectant solvent / in alcoholic drinks / antiseptic B1 | 1 |
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