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

Carboxylic acids and derivatives — practice question

An organic compound, $E$, has this mass composition: $\text{C}$, $48.7\%$; $\text{H}$, $8.1\%$; $\text{O}$, $43.2\%$.
(a)[2]

Calculate the empirical formula for $E$.

(b(i))[2]

In a suitable apparatus, $0.130\,\text{g}$ of $E$ was vaporised and took up $58.0\,\text{cm}^3$ at $127^{\circ}\text{C}$ and $1.00 \times 10^5\,\text{N m}^{-2}$. Use $pV = \frac{mRT}{M_r}$ to find $M_r$ of $E$, where $m$ represents the mass of $E$.

(b(ii))[2]

Therefore calculate the molecular formula of $E$.

(c)[3]

Compound $F$ is an ester with molecular formula $\text{C}_4\text{H}_8\text{O}_2$. $F$ is one of four isomers, $S$, $T$, $U$, and $V$, and all of them are esters. The structural formula of $S$ is shown in the boxes below. Draw the structural formulae of the other three ester isomers of $F$.

(d(i))[1]

When ester $F$ is hydrolysed, alcohol $G$ is formed. Which reagent can be used to hydrolyse an ester to an alcohol?

(d(ii))[1]

What other kind of organic compound is formed at the same time?

(e(i))[1]

On mild oxidation, alcohol $G$ produces compound $H$ which gives a silver mirror with Tollens’ reagent. What functional group does the reaction with Tollens’ reagent show is present in compound $H$? Name this group.

(e(ii))[1]

What type of alcohol is $G$?

(e(iii))[1]

What could the structural formula of alcohol $G$ be?

(f(i))[1]

Which of the four isomers, $S$, $T$, $U$, or $V$, could not be $F$?

(f(ii))[1]

Explain your answer.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: Mole ratio obtained correctly from the mass data

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