Question

The positive charge on sol particles of $AgI$ sol is due to preferential adsorption of _______ ions.
1. $I^{-}$
2. $A{g}^{+}$
3. both 1 and 2
4. none of the above

Answer 1

$AgI$ in contact with $AgN{O}_3$ forms positively charged colloid due to the adsorption of $A{g}^{+}$ ion.

$AgI+AgN{O}_3\to \left[AgI\right]A{g}^{+}:N{O}_3^{-}$

$AgI$ in contact with $KI$ forms negatively charged colloidal sol diue to the adsorption of $I^{-}$ ion.

$AgI+KI\to \left[AgI\right]I^{-}:K^{+}$