Chemistry 9701 · AS & A Level · Carboxylic acids and derivatives

Carboxylic acids and derivatives — practice question

A student combined an alcohol with a carboxylic acid under suitable conditions to make an ester. A sweet-smelling organic liquid, Q, with empirical formula $\text{C}_2\text{H}_4\text{O}$ was obtained. The $M_r$ of Q was determined experimentally to be $87.5$.
(a)[1]

State the molecular formula of Q.

(b)[4]

In the boxes below, draw the structural formulae of four ester isomers with this formula.

(c(i))[1]

What does the result of the test with Tollens’ reagent indicate about R?

(c(ii))[1]

What does the result of the test with 2,4-dinitrophenylhydrazine reagent indicate about R?

(c(iii))[1]

What functional group is shown to be present in R by the result of the test with sodium carbonate?

(d(i))[1]

What is the identity of the single organic compound, R?

(d(ii))[1]

Which of your structures, W, X, Y or Z, is the ester, Q?

(e)[1]

Which, if any, of your esters, W, X, Y or Z, is chiral?

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: The correct molecular formula is $\mathrm{C_4H_8O_2}$.

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