Carboxylic acids and derivatives — AS & A Level Chemistry (9701) questions by topic
Ester hydrolysis and acid-strength calculations run through this topic: drawing the displayed formula of ethanedioic acid, calculating a carboxylic acid's relative formula mass from gas produced with magnesium, and deducing an ester's molecular formula and hydrolysis products.
Deduce, identify, draw, state and explain lead 52 questions from 2023 to 2025 papers, worth 1 to 15 marks, where using the wrong molar gas volume is a frequent source of a wrong final figure. Instant marking after each calculation catches room-conditions versus s.t.p. molar-volume confusion, or a curly arrow drawn from the wrong atom, immediately rather than after the whole mechanism is submitted.
What examiners look for
- A common mistake was using the room-conditions molar volume of 24.0 dm3 instead of the s.t.p. value of 22.4 dm3, giving an incorrect relative formula mass.
- Examiners flag a curly arrow in the mechanism starting at the hydrogen rather than on the O-H bond itself, and an additional negative charge wrongly placed on the phenol oxygen.
- A recurring criticism is including an additional CH2 group, giving C6H5CH2COOH where a different structure was correct.
- Strong scripts used 380 cm3 at s.t.p. divided by 22400 to get 0.01696 mol of hydrogen, recognised two acid molecules react per H2 molecule, and reached a relative formula mass of 118.
- Candidates who drew out the skeletal structure first, before esterifying the remaining OH groups with ethanoic acid, correctly produced ester Z.
May–June 2025, Paper 11
Three reagents are listed. 1 aqueous sodium carbonate 2 LiAlH4 3 water Which reagents react with pure ethanoic acid to give a solution containing ethanoate ions? A 1 and 2 B 1 and…
Answer this question and get it marked →Which formula represents the organic compound formed by the reaction of propanoic acid with methanol in the presence of concentrated sulfuric acid as a catalyst? A CH3CH2COCH3 B…
Answer this question and get it marked →May–June 2025, Paper 12
An ester, R'CO2R'', is hydrolysed in alkaline conditions. R' and R'' are different alkyl groups. Which row identifies the two products formed? A product 1: R'CO2H, product 2:…
Answer this question and get it marked →Propanoic acid reacts with LiAlH4 to give organic product P. Methanoic acid reacts with organic product P, in the presence of a few drops of concentrated sulfuric acid, to give…
Answer this question and get it marked →May–June 2025, Paper 13
The structure of butenedioic acid is shown (trans-butenedioic acid / fumaric acid structure with C=C double bond). When an excess of NaOH(aq) is added to butenedioic acid, which…
Answer this question and get it marked →Four organic compounds are shown (a pentyl ester, methyl formate, an unsaturated ester, and an isobutyl ester). A mixture of these four compounds reacts with hot aqueous sodium…
Answer this question and get it marked →May–June 2025, Paper 21
Draw the structure of compound A (which hydrolyses to give malonic acid HOOCCH2COOH and 2 mol ethanol CH3CH2OH).
Answer this question and get it marked →May–June 2025, Paper 22
Propanoic acid, CH3CH2COOH, reacts with reducing agent Q to produce propan-1-ol, CH3CH2CH2OH. (i) Suggest the formula of reducing agent Q. (ii) Complete the equation to show the…
Answer this question and get it marked →May–June 2025, Paper 23
(i) Deduce the empirical formula of W (CH2=C(CH3)COOH, molecular formula C4H6O2). (ii) Two different reagents are each added to separate samples of W as shown in Table 5.1.…
Answer this question and get it marked →May–June 2025, Paper 24
An ester E has the molecular formula C5H10O2. Give the molecular formula of E.
Answer this question and get it marked →May–June 2025, Paper 41
Propanoic acid, methanoic acid and ethanedioic acid are all weak acids. Draw the displayed formula of ethanedioic acid.
Answer this question and get it marked →May–June 2025, Paper 43
Propanoic acid, methanoic acid and ethanedioic acid are all weak acids. Draw the displayed formula of ethanedioic acid.
Answer this question and get it marked →May–June 2025, Paper 44
Lavandulol (compound A, C₁₀H₁₈O) is a natural product found in lavender. It contains an alcohol group and two carbon–carbon double bonds. Compound A undergoes a series of…
Answer this question and get it marked →Benzoic acid, phenol and ethanol are three organic compounds. State and explain their relative acidities. Write equations to support your answer.
Answer this question and get it marked →May–June 2024, Paper 11
P is a carboxylic acid with molecular formula C5H10O2. Carboxylic acid P reacts with an excess of LiAlH4 to form compound Q. Which pairs of molecules could be carboxylic acid P…
Answer this question and get it marked →Compound X is treated with an excess of dilute aqueous potassium hydroxide. X is a six-membered lactone (cyclic ester) carrying a methyl substituent on the ring. What is the…
Answer this question and get it marked →May–June 2024, Paper 12
1 mole of each of the following four compounds is reacted separately with an excess of sodium and an excess of sodium carbonate. Which compound produces the same volume of gas…
Answer this question and get it marked →The diagrams show the structures of two esters, X and Y, that are formed in ripening apples. Ester X is 3-methylbutyl ethanoate (an ethanoate ester of a branched alcohol). Ester Y…
Answer this question and get it marked →May–June 2024, Paper 13
The Mr of compound X is 88. Compound X is heated under reflux with an excess of acidified potassium dichromate(VI) to produce compound Y. Compound Y reacts with compound X under…
Answer this question and get it marked →Which substance reacts with ethanoic acid to give the organic product with the highest Mr? A lithium aluminium hydride B magnesium C potassium carbonate D propan-2-ol
Answer this question and get it marked →A sample of propyl ethanoate is hydrolysed by heating under reflux with aqueous NaOH. The two organic products of the hydrolysis are separated, purified and weighed. Out of the…
Answer this question and get it marked →May–June 2024, Paper 41
May–June 2024, Paper 42
Explain why trichloroethanoic acid, CCl3COOH, is more acidic than ethanoic acid, CH3COOH.
Answer this question and get it marked →May–June 2024, Paper 43
October–November 2024, Paper 11
Compound Z has the molecular formula C₄H₈O₂. Compound Z reacts with propan-1-ol in the presence of concentrated H₂SO₄. The diagram shows the skeletal formulae of three esters S, T…
Answer this question and get it marked →(CH₃)₃CCN reacts to form alcohol Y via the reaction sequence shown. (CH₃)₃CCN reacts with H⁺(aq) in reaction 1 to give molecule X, and X reacts with LiAlH₄ in reaction 2 to give…
Answer this question and get it marked →October–November 2024, Paper 12
C₂H₅COOCH₃ is reacted with aqueous acid. The products from this reaction are reacted with LiAlH₄ to form two molecules Y and Z. What are the identities of molecules Y and Z? A…
Answer this question and get it marked →A sample of propanoic acid of mass 3.70 g reacts with an excess of magnesium. A second sample of propanoic acid of mass 3.70 g reacts with an excess of sodium. Both reactions go…
Answer this question and get it marked →Which statement about H₂C=C(CH₃)CH₂CO₂CH₃ is correct? A It can be hydrolysed to a secondary alcohol. B It can be made using ethanoic acid and a suitable alcohol. C It gives a…
Answer this question and get it marked →October–November 2024, Paper 13
Compound Z has the molecular formula C₄H₈O₂. Compound Z reacts with propan-1-ol in the presence of concentrated H₂SO₄. The diagram shows the skeletal formulae of three esters S, T…
Answer this question and get it marked →(CH₃)₃CCN reacts to form alcohol Y via the reaction sequence shown. (CH₃)₃CCN reacts with H⁺(aq) in reaction 1 to give molecule X, and X reacts with LiAlH₄ in reaction 2 to give…
Answer this question and get it marked →October–November 2024, Paper 42
Fig. 6.1 shows two reactions of ethanedioic acid, HOOCCOOH. HOOCCOOH reacts with an excess of SOCl2 to form organic product G. HOOCCOOH also reacts to give 2CO2 + H2O. (a)(i) Draw…
Answer this question and get it marked →February–March 2023, Paper 12
Tartaric acid, HOOCCH(OH)CH(OH)COOH, is found in many plants. A sample of tartaric acid reacts with an excess of LiAlH4 to form the organic product J. What happens when NaOH(aq)…
Answer this question and get it marked →The ester ethyl butanoate can be hydrolysed using an excess of dilute sodium hydroxide solution. Which substance is a product of this reaction? A CH3CH2CH2CO2Na B CH3CO2Na C…
Answer this question and get it marked →An aqueous solution contains 4.00 g of a carboxylic acid, Q. When this solution reacts with an excess of magnesium, 380 cm³ of gas is produced, measured at s.t.p. What is the…
Answer this question and get it marked →May–June 2023, Paper 11
Which method could produce butanoic acid? A an acid-base reaction involving CH3CH2CH2CO2Na B the hydrolysis of CH3CH2CH2CH2CN C the acidic hydrolysis of CH3CH2COOCH2CH2CH3 D the…
Answer this question and get it marked →Which ester may be hydrolysed to produce two products, one of which may be reduced to the other? A CH3CH2CO2CH3 B CH3CH(CH3)CO2CH2CH(CH3)2 C CH3CH2CO2CH(CH3)2 D (CH3)2CHCO2CH(CH3)2
Answer this question and get it marked →Two compounds, X and Y, are mixed and a little concentrated H2SO4 is added. Ester Z is found in the resulting mixture of products. Ester Z is a triester of propane-1,2,3-triol…
Answer this question and get it marked →May–June 2023, Paper 12
Which reaction will form propanoic acid? A acidic hydrolysis of propyl ethanoate B alkaline hydrolysis of ethyl propanoate C acidic hydrolysis of propanenitrile D acidic…
Answer this question and get it marked →Lactide is an intermediate in the manufacture of a synthetic fibre. Lactide is a six-membered ring containing two ester linkages (a cyclic di-ester) with two methyl substituents.…
Answer this question and get it marked →May–June 2023, Paper 13
Propanoic acid is treated with reagent X at room temperature. The organic product of the reaction is sodium propanoate. No gas is produced during the reaction. What could be…
Answer this question and get it marked →Compound Q can be hydrolysed by HCl(aq). The two products of this hydrolysis have the same empirical formula. What could Q be? A CH3CO2CH2CH2OH B CH3CO2CH2CH2CO2H C…
Answer this question and get it marked →An unsaturated carboxylic acid reacts with alcohol X to form an ester. The structure of the ester is shown: it is the ester of an unsaturated carboxylic acid (containing a C=C…
Answer this question and get it marked →May–June 2023, Paper 21
V is a colourless liquid. Fig. 4.1 shows the structure of V: it is but-3-enoic acid, CH2=CHCH2CO2H (a carboxylic acid with a terminal C=C double bond). V reacts with an excess of…
Answer this question and get it marked →October–November 2023, Paper 11
Propanoic acid can be made from bromoethane using a two-stage synthesis. Which pair of reagents is most suitable? A: stage 1 hydrogen cyanide, stage 2 aqueous sodium hydroxide. B:…
Answer this question and get it marked →The structure of compound X is shown - a five-membered cyclic ester (a gamma-lactone) bearing a methyl substituent on the carbon next to the ring oxygen. What is produced when X…
Answer this question and get it marked →October–November 2023, Paper 12
Three equations are shown: 1 CH3COOH + MgCO3 - CH3COOMg + CO2 + H2O; 2 CH3CH2COOH + Na - CH3CH2COONa + 1/2H2; 3 CH3CH2COOH + 2Ba(OH)2 - CH3CH2COOBa2 + 2H2O. Which of the equations…
Answer this question and get it marked →How many esters with the molecular formula C5H10O2 can be made by reacting a primary alcohol with a carboxylic acid? A: 4. B: 5. C: 6. D: 8.
Answer this question and get it marked →The diagram shows an ester (ethyl propanoate). It is heated under reflux with an excess of NaOH(aq). Which row shows the 2 products of the reaction? A: product 1 propanoic acid,…
Answer this question and get it marked →October–November 2023, Paper 13
The structure of compound X is shown. [The skeletal structure of compound X is shown: a five-membered lactone (gamma-butyrolactone ring) bearing a CH3 substituent on the carbon…
Answer this question and get it marked →October–November 2023, Paper 41
Benzoyl chloride, C₆H₅COCl, can be made from ethyl benzene in a two-step process: ethyl benzene → compound M (step 1) → benzoyl chloride (step 2). Draw the intermediate organic…
Answer this question and get it marked →October–November 2023, Paper 43
Benzoyl chloride, C₆H₅COCl, can be made from ethyl benzene in a two-step process: ethyl benzene → compound M (step 1) → benzoyl chloride (step 2). Draw the intermediate organic…
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