Question

A compound $\mathrm{C}$(molecular formula, ${\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{O}}_2$) reacts with $\mathrm{Na}$ – metal to form a compound $\mathrm{R}$and evolves into a gas which burns with a pop sound. Compound $\mathrm{C}$ on treatment with an alcohol $\mathrm{A}$in presence of an acid forms a sweet-smelling compound $\mathrm{S}$ (molecular formula, ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_2$). On addition of $\mathrm{NaOH}$ to $\mathrm{C}$, it also gives $\mathrm{R}$ and water. $\mathrm{S}$ on treatment with $\mathrm{NaOH}$ solution gives back $\mathrm{R}\mathrm{and}\mathrm{A}$. Identify $\mathrm{C},\mathrm{R},\mathrm{A},\mathrm{S}$ and write down the reactions involved?

Answer 1

Identification of the compounds $\mathrm{C},\mathrm{R},\mathrm{A},\mathrm{S}$ and their chemical reactions:

• Here Compound 'C' is Ethanoic acid which is known to have a molecular formula
• It reacts with sodium to form Sodium ethanoate which is denoted as the compound 'R' and the evolved hydrogen gas during the reaction burns with a pop sound.
• The chemical equation related to the above reaction can be given as:
  $\underset{\left(\mathrm{C}\right)}{\underset{\left(\mathrm{Ethanoic}\mathrm{acid}\right)}{2{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{s}\right)}}+\underset{\left(\mathrm{Sodium}\right)}{2\mathrm{Na}\left(\mathrm{s}\right)}\to \underset{\left(\mathrm{R}\right)}{\underset{\left(\mathrm{Sodium}\mathrm{ethanoate}\right)}{2{\mathrm{CH}}_3\mathrm{COONa}\left(\mathrm{s}\right)}}+\underset{\left(\mathrm{Hydrogen}\mathrm{gas}\right)}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$
• Further, when Ethanoic acid reacts with methanol in the presence of an acid, it forms methyl ethanoate ester which is a sweet-smelling substance with the molecular formula, ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_2$.
• Here, compound S is Methyl ethanoate and A is Methanol.
• The chemical equation related to the above reaction can be given as:
• $\underset{\left(C\right)}{\underset{\left(\mathrm{Ethanoic}\mathrm{acid}\right)}{{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)}}+\underset{\left(\mathrm{A}\right)}{\underset{\left(\mathrm{Methanol}\right)}{{\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{aq}\right)}}\stackrel{\mathrm{acid}}{\to }\underset{\left(\mathrm{s}\right)}{\underset{\left(\mathrm{Methyl}\mathrm{ethanoate}\right)}{{\mathrm{CH}}_3{\mathrm{COOCH}}_3\left(\mathrm{aq}\right)}}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$
• When sodium hydroxide is added to ethanoic acid, it gives Sodium ethanoate (S) and water.
• The chemical equation related to the above reaction can be given as:
  $\underset{\left(C\right)}{\underset{\left(\mathrm{Ethanoic}\mathrm{acid}\right)}{{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)}}+\underset{\left(\mathrm{Sodium}\mathrm{hydroxide}\right)}{\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{\left(\mathrm{R}\right)}{\underset{\left(\mathrm{Sodium}\mathrm{ethanoate}\right)}{{\mathrm{CH}}_3\mathrm{COONa}\left(\mathrm{aq}\right)}}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$
• When Methyl ethanoate(S) is treated with $\mathrm{NaOH}$ solution, it gives back Methanol and Sodium ethanoate as compounds A and R respectively.
• The chemical equation related to the above reaction can be given as:
  $\underset{\mathrm{S}}{\underset{\left(\mathrm{Methyl}\mathrm{ethanoate}\right)}{{\mathrm{CH}}_3{\mathrm{COOCH}}_3\left(\mathrm{aq}\right)}}+\underset{\left(\mathrm{Sodium}\mathrm{hydroxide}\right)}{\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{\mathrm{A}}{\underset{\left(\mathrm{Methanol}\right)}{{\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{aq}\right)}}+\underset{\mathrm{R}}{\underset{\left(\mathrm{Sodium}\mathrm{ethanoate}\right)}{{\mathrm{CH}}_3\mathrm{COONa}\left(\mathrm{aq}\right)}}$

Hence,

Compound C is ${\mathrm{CH}}_3\mathrm{COOH}$ (Ethanoic acid).
Compound R is ${\mathrm{CH}}_3\mathrm{COONa}$ (Sodium ethanoate).
Compound A is ${\mathrm{CH}}_3\mathrm{OH}$ (Methanol).
Compound S is ${\mathrm{CH}}_3{\mathrm{COOCH}}_3$​ (Methyl ethanoate).