Question

A when added to silica gives B. A and B are:

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

$H_{2}C{O}_{3\left(aq\right)}+H_2{O}_{\left(l\right)}\rightleftharpoons HC{O}_{3\left(aq\right)}^{\ominus }+H_3{O}_{\left(aq\right)}^{\ominus }$

$HC{O}_{3\left(aq\right)}^{\ominus }+H_2{O}_{\left(l\right)}\rightleftharpoons C{O}_{3\left(aq\right)}^{2-}+H_3{O}_{\left(aq\right)}^{\ominus }$

Silica is readily attacked by HF, resulting in the formation of $Si{F}_4$.

$Si{O}_2+4HF\to Si{F}_4+2H_{2}O$

$Si{F}_4$ thus formed dissolves in HF, forming hydroflurosilicic acid.

$Si{F}_4+2HF\to H_{2}Si{F}_6$

Due to the formation of $H_{2}Si{F}_6,Si{O}_2$ present in glass dissolves. Therefore, HF cannot be stored in glass bottles.

$4HF+Si{O}_2\to H_{2}Si{F}_4+H_{2}O$

$\downarrow \downarrow$

$AB$