Question

Hydrolysis of $SiC{{l}_{4}}$ gives compound X and HCl. On heating to $1000{}^{0}C$ X loses water and forms Y. Identify X and Y.
A. $Si{{O}_{2}},Si$
B. ${{H}_{4}}Si{{O}_{4}},Si{{O}_{2}}$
C. $Si{{O}_{2}},SiC$
D. ${{H}_{2}}Si{{O}_{4}},Si$

Answer 1

Hydrolysis is a type of decomposition reaction where one of the reactants is water and typically water is used to break chemical bonds in the other reactant. Over here this hydrogen of water will try to out chlorine as a chloride ion and the remaining hydroxide ion will try to replace it. So over here in the hydrolysis of silicon tetrachloride, each chloride ion will be substituted by a hydroxide ion.

Complete step by step answer:
$SiC{{l}_{4}}$ is a colorless, fuming liquid with a pungent odor. It is decomposed by water to hydrochloric acid with the evolution of heat. It is corrosive to metals and tissue in the presence of moisture.
- ${{H}_{2}}O$ is a polar protic solvent that can also have the capability of reacting with many compounds and elements and making a new product with them via hydrolysis. Water doesn’t react with carbon tetrachloride but it does hydrolyze the silicon tetrachloride and forms an acid.
$SiC{{l}_{4}}$​ on hydrolysis gives Ortho silicic acid according to the following reaction:
$SiC{{l}_{4}}+4{{H}_{2}}O\to Si{{\left( OH \right)}_{4}}+4HCl$
- As in silicic acid 4 hydroxide group are attached to one silicon atom so it is not very stable, therefore on rigorous heating silicic acid loses water and forms silica ${{H}_{4}}Si{{O}_{4}}\xrightarrow{1000{}^{0}C}Si{{O}_{2}}+2{{H}_{2}}O$
The correct answer is option “B” .

Additional Information : Hydrolysis may be considered as the reverse of a condensation reaction in which two molecules combine with each-other and release a water molecule and form a new product.

Note: Silicic acid is a compound of silicon, oxygen, and hydrogen, regarded as the parent substance from which is derived a large family, the silicates of minerals, salts, and esters. The acid can be prepared only as an unstable solution in water; its molecules readily condense with one another to form water and polymeric chains, rings, sheets, or three-dimensional networks that constitute the structural units of silica gel and many minerals that have very low solubility in water.