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S5 Chemistry: Alcohols, Carboxylic Acids and Esters (Paper 1: Basics)
S5 Chemistry: Alcohols, Carboxylic Acids and Esters (Paper 1: Basics)
Ten items on functional groups, ester names and mole calculations for fermentation and esterification.
Direct answers Answers in order: C2H6O, the carboxyl group, carbon dioxide, hydrogen, 1.0 mol/dm3, 60, ethyl ethanoate, 1.0 mol, 17.6 g, esterification is reversible.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S5 Chemistry: Alcohols, Carboxylic Acids and Esters |
| Level | S5 |
02 Questions (10 items)
- FoundationWhat is the molecular formula of ethanol?
- FoundationWhat is the functional group of a carboxylic acid?
- FoundationWhich gas is released along with ethanol when glucose ferments?
- IntermediateWhich gas is released when ethanol reacts with sodium?
- Intermediate4.6 g of ethanol is made up to 100 cm3 of solution. What is the concentration? (Mr of ethanol 46)
- IntermediateWhat is the relative molecular mass of ethanoic acid? (C 12, H 1, O 16)
- ChallengeEthanol and ethanoic acid are warmed with concentrated sulphuric acid. Which ester forms?
- Challenge0.50 mol of glucose is fully fermented. What is the maximum amount of ethanol in moles?
- Challenge0.20 mol of ethanol reacts with excess ethanoic acid. What mass of ethyl ethanoate can form? (Mr 88)
- Error redoError replay: a student claims esterification goes to completion. What is correct?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | C2H6O (that is, C2H5OH) | Ethanol has two carbons, six hydrogens and one oxygen, with an OH group on the chain. |
| 2 | The carboxyl group (COOH) | A carboxyl group is a carbonyl carbon bonded to an OH group, so it is both acidic and esterifiable. |
| 3 | Carbon dioxide | Yeast breaks glucose down into ethanol and carbon dioxide without oxygen. |
| 4 | Hydrogen | Sodium replaces the hydrogen of the OH group and two atoms pair into hydrogen gas. |
| 5 | 1.0 mol/dm3 | Divide 4.6 by 46 to get 0.10 mol, then divide by 0.100 dm3 of solution. |
| 6 | 60 | Two carbons, four hydrogens and two oxygens give 24 plus 4 plus 32. |
| 7 | Ethyl ethanoate | The acid loses OH and the alcohol loses H; the ester is named alcohol part first, then acid part. |
| 8 | 1.0 mol | Each mole of glucose gives two moles of ethanol, so the amount doubles. |
| 9 | 17.6 g | The alcohol and the ester are one to one, giving 0.20 mol, which weighs 17.6 g. |
| 10 | Esterification is reversible, so the yield stays below one hundred per cent | The ester hydrolyses back to acid and alcohol, so the system settles at equilibrium. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
When you meet an ester name, ask first which alcohol the first part came from.Tutor Registration →
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