Identify what information from the spectrum allows the determination of the relative numbers of hydrogen atoms producing each peak.

Deduce which of the following compounds is Q.

\[{\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{3}}}\quad \quad \quad \quad \quad {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COC}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{3}}}\quad \quad \quad \quad \quad {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{OH}}\]

Identify the wavenumbers of two peaks in the infrared spectrum of compound Q, using Table 17 of the Data Booklet.

(ratio of) area under each peak / integration trace;

Accept size of peak but not height of peak.

\({\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COC}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{3}}}\);

1700–1750 \({\text{(c}}{{\text{m}}^{ - 1}}{\text{)}}\) and 2850–3100 \({\text{(c}}{{\text{m}}^{ - 1}}{\text{)}}\);

Accept a single value or a smaller range within each range.

This was a well-answered question generally. In part (a) most candidates recognized the area under the peak as the indicator of the number of hydrogen atoms in NMR spectroscopy, although few candidates thought it was the chemical shift, and few candidates incorrectly stated that it was the height of the peak (rather than the area underneath it).

This was a well-answered question generally. The majority of candidates chose the correct molecule (pentan-2-one) in part (b) and gave the correct ranges of IR absorptions in part (c).

This was a well-answered question generally. The majority of candidates chose the correct molecule (pentan-2-one) in part (b) and gave the correct ranges of IR absorptions in part (c).