CAIE A Level Chemistry 9701 · Analytical techniques
A sample of propanal, , is dissolved in a deuterated solvent and its proton NMR spectrum is recorded. The spectrum shows three peaks, with relative peak areas in the ratio 3 : 2 : 1. TMS is added as a reference.
Explain how this spectrum allows the three different types of proton environment in propanal to be identified, and why deuterated solvent and TMS are used.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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