Question

A chemical ${}^{\prime }A’$ is used for the preparation of washing soda to recover ammonia. When $C{O}_2$ is bubbled through an aqueous solution of ${}^{\prime }A’$, the solution turns milky. It is used in white washing due to disinfectant nature. What is the chemical formula of ${}^{\prime }{A}^{\prime }$ ?

• A. $Ca(HC{O}_3{)}_2$
• B. $CaO$
• C. $Ca(OH{)}_2$
• D. $CaC{O}_3$

Answer 1

Answer: (C)

$Ca(OH{)}_2$ is used in Solvay process i.e., preparation of washing soda $(N{a}_{2}C{O}_3\cdot 10H_{2}O)$ to recover $N{H}_3$.
$2N{H}_{4}Cl+\underset{{}^{\prime }{A}^{\prime }}{Ca(OH{)}_2}\to 2N{H}_3+CaC{l}_2+H_{2}O$
$\underset{{}^{\prime }{A}^{\prime }}{Ca(OH{)}_2}+C{O}_2\to \underset{\text{Milkincss}}{CaC{O}_3\downarrow }+H_{2}O$
$Ca(OH{)}_2$ is used in white washing due to its disinfectant nature.