Question

One mole of $P _{2} O _{5}$ undergoes hydrolysis as $P _{2} O _{5}+ H _{2} O \rightarrow H _{3} PO _{4}$ The normality of the phosphoric acid formed is (The volume of solution is $1\, L$ )

• A. 2
• B. 12
• C. 24
• D. 4

Answer 1

Answer: (B)

12

Answer 2

$\underset{1 \,mol }{ P _{2} O _{5}}+6 H _{2} O \rightarrow \underset{4\, mol }{4 H _{3} P O _{4}}$
$\therefore 1 \,L$ solution contains $4 \,mol\, H _{3} P O _{4}$
$\therefore$ Molarity of $H _{3} PO _{4}=4 \,M$
Normality $=$ Molarity $x$ Basicity
$=4 \times 3 \,N =12\, N$