The pH value of decinormal solution of NH4OH which is 20 % ionised is

Question

The pH value of decinormal solution of NH4OH which is 20 % ionised is (A) 12.95 (B) 12.30 (C) 14.70 (D) 13.30

Tardigrade Admin · Accepted Answer

Concentration of NH4OH solution = 0.1 N Concentration of OH - ions in solution, [OH-] = 20 % of 0.1 N = (20/100)× 0.1 = 0.02 N ⇒ pOH = - [logOH-] = - log (0.02) = 2 - 0.301 ⇒ pH = 14 - pOH = 12.30

Q. The $p H$ value of decinormal solution of $N H_{4} O H$ which is $20%$ ionised is

12.95

12.30

14.70

13.30

Concentration of $N H_{4} O H$ solution $= 0.1 N$

Concentration of $O H$ - ions in solution,

$[O H^{-}] = 20%$ of $0.1 N = \frac{20}{100} \times 0.1$

$= 0.02 N$

$\Rightarrow pO H = - [l o g O H^{-}] = - l o g (0.02)$

$= 2 - 0.301$

$\Rightarrow p H = 14 - pO H = 12.30$

Q. The pH value of decinormal solution of NH4​OH which is 20% ionised is