Q.
The dissolution of ammonia gas in water does not obey Henry's law. On dissolving, a major portion of ammonia, molecules unite with $H _2 O$ to form $NH _4 OH$ molecules. $NH _4 OH$ again dissociate into $NH _4^{+}$and $OH ^{-}$ions. In solution therefore, we have $NH _3$ molecules, $NH _4 OH$ molecules and $NH _4^{+}$ions and the following equilibrium exist:
$NH _3( g )$ (pressure $p$ and concentration $C$ ) initially $\rightleftharpoons NH _3(l)+ H _2 O \rightleftharpoons NH _4 OH \rightleftharpoons NH _4^{+}+ OH ^{-}$
Let $C_1 \, mol / L$ of $NH _3$ pass in solution state a part of which on dissolution in water forms $C_2\, mol / L$ of $NH _4 OH$. The solution contains $C_3 \, mol / L$ of $NH _4^{+}$ions
Total concentration of ammonia, which can be determined by volumetric analysis is equal to:
Equilibrium
Solution: