Question

$HCN+H_{2}O\to \left[X\right]+N{H}_3\text{,}$
$\left[X\right]\to \left[Y\right]+H_{2}O$ Unbalanced equations
$[Y]$ May be prepared by which one of the following methods?

• A. By dehydration of Malonic acid with $P_2{O}_5$
• B. By thermal decomposition of carbon sub-oxide in air.
• C. By heating potassium hexacyanoferrate (II) with conc. $H_{2}S{O}_4$ .
• D. By the action of conc. $HN{O}_3$ on charcoal.

Answer 1

Answer: (C)

$HCN\text{ + }2H_{2}O\to HCOOH\left(X\right)\text{ + }2N{H}_3;$
$HCOOH\stackrel{\Delta }{\to }CO\left[Y\right]\text{+}{H}_{2}O$
(i) Malonic acid on dehydration by $P_2{O}_5$ produce $C_3{O}_2$ .
(ii) Carbon suboxide gives $C{O}_2$ on dissociation.
(iii) Potassium ferrocyanide on reaction with concentrated sulphuric acid produce $CO$ gas.
(iv) Action of concentrated $HN{O}_3$ on charcoal gives $C{O}_2$ .