Question

An organic compound ‘A’ is widely used as a preservative in pickles and has the molecular formula ${\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{O}}_2$. This compound reacts with Ethanol to form a sweet-smelling compound ‘B’.

1. Identify the compound ‘A’
2. Write the chemical equation for its reaction with Ethanol to form compound ‘B’
3. How can we get compound ‘A’ back from ‘B’?
4. Name the process and write the corresponding chemical equation
5. Which gas is produced when compound ‘A’ reacts with washing soda? write the chemical equation

Answer 1

1.

• ‘A’ with molecular formula ${\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{4}}{\mathbf{O}}_{\mathbf{2}}$ is an Ethanoic acid.

2.

• Compound A reacted with Ethanol to give a compound ‘B’ which is an Ester and has a fruity smell.
• The compound 'B' = Ethyl acetate (${\mathbf{CH}}_{\mathbf{3}}{\mathbf{COOC}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}$).
• The process is called Esterification.

1. $$\begin{gathered} {\mathbf{CH}}_{\mathbf{3}}\mathbf{COOH}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}\mathbf{OH}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{CH}}_{\mathbf{3}}{\mathbf{COOC}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)} \\ \mathbf{Ethanoic}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Ethanol}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Ethyl} \\ \mathbf{acid}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{acetate} \end{gathered}$$

3.

• We can get back A from B by reacting Ethyl acetate (${\mathbf{CH}}_{\mathbf{3}}{\mathbf{COOC}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}$ ) with the water in presence of acid.

4.

• ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{COOC}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\stackrel{\mathbf{dil}\mathbf{}\mathbf{HCl}}{\mathbf{\to }}\mathbf{}{\mathbf{CH}}_{\mathbf{3}}\mathbf{COOH}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}\mathbf{OH}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}$.
• The reaction is called Saponification or Ester Hydrolysis.

5.

• When Ethanoic acid reacts with Sodium Carbonate/ washing soda then ${\mathbf{CO}}_{\mathbf{2}}$ gas is produced.
• $$\begin{gathered} {\mathbf{CH}}_{\mathbf{3}}\mathbf{COOH}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{Na}}_{\mathbf{2}}{\mathbf{CO}}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}\mathbf{2}{\mathbf{CH}}_{\mathbf{3}}\mathbf{COONa}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{CO}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sodium} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Carbonate} \end{gathered}$$