Chemistry 9701 · AS & A Level · Carbonyl compounds

Carbonyl compounds — practice question

For this question, you may assume that $^1\text{H}$ and $^3\text{H}$ show identical chemical behaviour. A sample of ethanal contains only the hydrogen isotope $^1\text{H}$. It is converted into compound $Z$, $\text{C}_2\text{H}_6\text{O}$, by a nucleophilic addition reaction with NaBH$_4$. Every hydrogen atom in the NaBH$_4$ is the $^3\text{H}$ isotope. $\text{CH}_3\text{CHO} \xrightarrow[]{\text{NaBH}_4} \text{C}_2\text{H}_6\text{O}$ Compound $Z$ is then oxidised to ethanal and water. $\text{C}_2\text{H}_6\text{O} + [O] \rightarrow \text{CH}_3\text{CHO} + \text{H}_2\text{O}$ Which statement about the final product mixture is correct?

  • ABoth ethanal and water contain $^3\text{H}$ atoms.
  • BEthanal is the only product containing $^3\text{H}$ atoms.
  • CNeither ethanal nor water contain $^3\text{H}$ atoms.
  • DWater is the only product containing $^3\text{H}$ atoms.

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