Question

${\text{SiC}}{{\text{l}}_4}{\text{ }}\xrightarrow{{{H_2}O}}{\text{X }}\xrightarrow{{heat}}{\text{ Y }}\xrightarrow{{NaOH}}{\text{ Z}}$
X,Y, and Z in the above reaction are:
(A) ${\text{X}} - {\text{ Si}}{{\text{O}}_2}{\text{, Y}} - {\text{ Si, Z}} - {\text{ NaSi}}$
(B) ${\text{X}} - {\text{ Si}}{\left( {{\text{OH}}} \right)_4}{\text{, Y}} - {\text{ Si}}{{\text{O}}_2}{\text{, Z}} - {\text{ N}}{{\text{a}}_2}{\text{Si}}{{\text{O}}_3}$
(C) ${\text{X}} - {\text{ Si}}{\left( {{\text{OH}}} \right)_4}{\text{, Y}} - {\text{ Si, Z}} - {\text{ Si}}{{\text{O}}_2}$
(D) ${\text{X}} - {\text{ Si}}{{\text{O}}_2}{\text{, Y}} - {\text{ SiC}}{{\text{l}}_4}{\text{, Z}} - {\text{ N}}{{\text{a}}_2}{\text{Si}}{{\text{O}}_3}$

Answer 1

Hydrolysis of silicon tetrachloride gives orthosilicic acid. Thermal decomposition of orthosilicic acid gives silicon dioxide. Acidic silicon dioxide reacts with sodium hydroxide base to form salt and water.

Complete step by step answer:
The chemical formula ${\text{SiC}}{{\text{l}}_4}$ represents silicon tetrachloride compounds.
The reaction of silicon tetrachloride with water is a hydrolysis reaction. The products of the hydrolysis reaction of silicon tetrachloride with water are orthosilicic acid and hydrogen chloride. Write the balanced chemical equation for the reaction:
${\text{SiC}}{{\text{l}}_4}{\text{ + 4}}{{\text{H}}_2}{\text{O }}\xrightarrow{{hydrolysis}}{\text{ Si}}{\left( {{\text{OH}}} \right)_4}{\text{ + 4HCl}}$
In the above reaction, the four silicon-chlorine bonds break and four silicon-oxygen bonds are formed. Similarly, four oxygen-hydrogen bonds break and form hydrogen-chlorine bonds. Four chlorine atoms of silicon tetrachloride are replaced with four hydroxyl groups.
Hence, X is ${\text{Si}}{\left( {{\text{OH}}} \right)_4}$.
When orthosilicic acid ${\text{Si}}{\left( {{\text{OH}}} \right)_4}$ is heated further, it loses two water molecules to form silicon dioxide. Hence, Y is ${\text{Si}}{{\text{O}}_2}$ . Write the balanced chemical equation for the process:
${\text{Si}}{\left( {{\text{OH}}} \right)_4}{\text{ }}\xrightarrow{\Delta }{\text{ Si}}{{\text{O}}_2}{\text{ + 2}}{{\text{H}}_2}{\text{O}}$
Silicon dioxide is acidic oxide. It reacts with bases (such as sodium hydroxide) to form salt and water.
Write the balanced chemical equation for the process:
${\text{Si}}{{\text{O}}_2}{\text{ + 2NaOH }} \to {\text{ N}}{{\text{a}}_2}{\text{Si}}{{\text{O}}_3}{\text{ + }}{{\text{H}}_2}{\text{O}}$
Hence, Z is ${\text{N}}{{\text{a}}_2}{\text{Si}}{{\text{O}}_3}$ .

Hence, the correct answer is the option (B) ${\text{X}} - {\text{ Si}}{\left( {{\text{OH}}} \right)_4}{\text{, Y}} - {\text{ Si}}{{\text{O}}_2}{\text{, Z}} - {\text{ N}}{{\text{a}}_2}{\text{Si}}{{\text{O}}_3}$.

Note: Silicon dioxide is a covalent compound with tetrahedral geometry. Silicon dioxide is highly unreactive. It does not react with most acids, halogens and alkalis. But it reacts with sodium hydroxide and hydrogen fluoride.