Question

The presence of $N{H}_{4}Cl$ in the test solution while precipitating group $III-A$ hydroxides (in qualitative inorganic analysis) helps in

• A. lowering $\left[O{H}^{-}\right]$
• B. lowering $\left[N{H}_{4}OH\right]$
• C. increasing $\left[O{H}^{-}\right]$
• D. increasing $\left[N{H}_{4}OH\right]$

Answer 1

The correct option is A lowering $\left[O{H}^{-}\right]$

$N_{4}OH\to N{H}_4^{+}+O{H}^{-}$

$N{H}_{4}Cl\to N{H}_4^{+}+C{l}^{-}$

$N{H}_{4}Cl$ decreases the dissociation of $N{H}_{4}OH$ by common ion effect where $N{H}_4^{+}$ acts as common ion.