Chemistry 9701 · AS & A Level · Analytical techniques

Analytical techniques — practice question

$V$ exhibits stereoisomerism.
(a(i))[1]

Explain what stereoisomerism means.

(a(ii))[2]

Deduce how many stereoisomers $V$ has. Explain your reasoning.

(a(iii))[1]

Deduce the molecular formula of $V$.

(a(iv))[1]

Name all the functional groups present in $V$.

(b(i))[1]

Identify the role of reagent T for each functional group that reacts in reaction 1.

(b(ii))[1]

Suggest the identity of reagent U in reaction 2.

(c(i))[2]

Part of the mass spectrum for Q is shown in Fig. 6.4. Only peaks with $m/e$ greater than 198 are shown. Calculate the relative abundance, $x$, of the peak at $m/e = 201$. Show your working.

(c(ii))[1]

Q contains only hydroxyl functional groups. Complete Table 6.1 to show the observations that occur when 2,4-dinitrophenylhydrazine (2,4-DNPH reagent) is added to separate samples of Y and Q.

(c(iii))[2]

Under certain conditions, $0.0020\ \text{mol}$ of Q reacts with an excess of sodium to produce a total of $44.8\ \text{cm}^3$ of gas at s.t.p. Calculate the number of hydroxyl groups present in a molecule of Q. Show your working.

(c(iv))[2]

Use Table 6.2 to describe and explain two differences between the infrared spectrum of Y and Q in the region above $1500\ \text{cm}^{-1}$.

(iii)[2]

Under certain conditions, $0.0020\ \text{mol}$ of Q reacts with an excess of sodium to produce a total of $44.8\ \text{cm}^3$ of gas at s.t.p. Calculate the number of hydroxyl groups present in a molecule of Q. Show your working.

(iv)[2]

Use Table 6.2 to describe and explain two differences between the infrared spectrum of Y and Q in the region above $1500\ \text{cm}^{-1}$.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: identical structural and molecular formulae but a different spatial arrangement

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