Chemistry 9701 · AS & A Level · Analytical techniques

Analytical techniques — practice question

This question concerns compound $T$, $\text{C}_x\text{H}_y\text{O}_z$. A section of the mass spectrum for $T$ is shown. The peak heights of the $M$ and $M+1$ peaks are 33.9 and 3.4 respectively.
(a(i))[2]

Calculate $x$, the count of carbon atoms in $T$.

(a(ii))[1]

Deduce the molecular formula for $T$.

(a(iii))[1]

There is a peak at $m/e = 119$ in the mass spectrum. Identify the fragment lost from $T$ to give this peak.

(b)[1]

Use the Data Booklet to identify the bond type responsible for each of the peaks $V$ and $W$. Write your answers for $V$ and $W$.

(c(i))[1]

Fill in the table for the proton NMR spectrum of $T$ using the Data Booklet.

(c(ii))[1]

The peak at $\delta = 2.4\ \text{ppm}$ comes from a proton attached to a saturated carbon atom. State the two possible proton types.

(c(iii))[1]

Adding $\text{D}_2\text{O}$ to $T$ leaves its proton NMR spectrum unchanged. What does this show about the functional groups present in $T$?

(d)[2]

Using the information, draw two possible structures of $T$ that are functional group isomers of one another.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Working gives $n=9.1$, so there are 9 carbon atoms

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