Question

When phosphorus reacts with caustic soda, the products are $PH _{3}$ and $NaH _{2} PO _{2}$. This reaction is an example of

• A. oxidation
• B. reduction
• C. disproportionation
• D. none of these

Answer 1

Answer: (C)

disproportionation

Answer 2

$\overset{0}{P}_{4}+3 N a O H+3 H_{2} O \rightarrow \overset{-3}{P} H_{3}+3 N a H_{2} \overset{+1}{P} O_{2}$ Oxidation number of $P$ changes from zero to $-3$ in $PH _{3}$ and $+1$ in $NaH _{2} PO _{2}$. Therefore, it is an example of disproportionation reaction.