IB Chemistry HL 3.2.12 Combined Data Analysis Question Bank

Practise HL 3.2.12 combined data analysis by reading structural and spectroscopic evidence, then selecting the explanation supported by the data.

Exam points

identify the diagnostic structural or spectral feature
match peaks, splitting or stereochemical relationships to the correct structure
combine independent evidence before making the final deduction

[Maximum number: 3]

This question is about carbon and chlorine compounds.

The mass and ${ }^{1} \mathrm{H}$ NMR spectra of product X are shown below. Deduce, giving your reasons, its structural formula and hence the name of the compound.

Mass spectrum:

Figure for Question 3.2.12 (HL)—Combined data analysis question 1 — IB Chemistry HL

${ }^{1} \mathrm{H}$ NMR spectrum:

molecular ion peak(s) «about» m/z 100 AND «so» $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}$ «isotopes of Cl»

two signals «in ${ }^{1} \mathrm{H}$ NMR spectrum» AND «so» $\mathrm{CH}_{3} \mathrm{CHCl}_{2}$

OR

«signals in» 3:1 ratio «in ${ }^{1} \mathrm{H}$ NMR spectrum» AND «so» $\mathrm{CH}_{3} \mathrm{CHCl}_{2}$

OR

one doublet and one quartet «in ${ }^{1} \mathrm{H}$ NMR spectrum» AND «so» $\mathrm{CH}_{3} \mathrm{CHCl}_{2}$

1,1-dichloroethane

Marking guidance:

Accept "peaks" for "signals".

Allow ECF for M3 if the formula of an incorrect chlorohydrocarbon is identified.

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3.2.12 (HL)—Combined data analysis question 1