Question

What is the role of $CaO$ in the soda-lime process?

• A. It facilitates decarboxylation by absorbing $C{O}_2$
• B. Being porous, increases the surface area of mixture
• C. It reacts with $C{O}_2$ to form $CaC{O}_3$
• D. All of the above

Answer 1

The correct option is D All of the above

When sodium carboxylate reacts with soda lime $(NaOH+CaO)$ it gives hydrocarbons.
It is a decarboxylation reaction. Here, $C{O}_2$ escapes to form a carbanion which absorbs a proton to form respective hydrocarbons.
Role of $CaO$ in the reaction:
$CaO$ being porous increases the surface area of mixture, thereby, facilitating decarboxylation by absorbing $C{O}_2$.
$CaO$ absorbs $C{O}_2$ only to form $CaC{O}_3$, but since NaOH is in the solution, it reacts further with $CaC{O}_3$ to give $N{a}_{2}C{O}_3$.

Hence, option (d) is correct.