Question

Do you expect different products in solution when aluminium(III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified the water, and (iii) alkaline water? Write equations wherever necessary.

Answer 1

$KCl$ is a salt of strong acid $HCl$ and strong base $KOH$. Such salts are neutral in nature and do not undergo hydrolysis. In neutral water, acidic water and alkaline water, $KCl$ dissociates as
$KCl\stackrel{Water}{\to }{K}^{+}+C{l}^{-}$
$AlC{l}_3$ is a salt of strong acid $HCl$ and weak base $Al(OH{)}_3$.
In normal water, it is hydrolyzed.
$AlC{l}_3+3H_{2}O\to Al(OH{)}_3+3H^{+}+3C{l}^{-}$
In acidic water, $H^{+}$ ions react with $Al(OH{)}_3$ forming water and $A{l}^{3+}$ ions. Hence it exists as $A{l}^{3+}+C{l}^{-}$
$AlC{l}_3\underset{water}{\overset{acidified}{\to }}A{l}^{+}+3C{l}^{-}$
In alkaline water, the reaction is
$Al(OH{)}_3+O{H}^{-}\to [Al(OH{)}_4{]}^{-}$