(a) Adsorption of a gas on surface of solid is generally accompained by a
decrease in entropy, still it is a spontaneous process. Explain.
(b) Some substances can act both as colloids and crystalloids. Explain.
(c) What will be the charge on AGI colloidal particles when it is prepared
by adding small amount of solution to KI solution in water?
What is responsible for the development of this charge?
We know for adsorption. are negative
and . Thus from this equation is negative. Therefore,
for adsorption all are negative.
(b) A crystalloid can be found to behave as a colloid under a different
set of conditions and vice-versa.
Example: NaCl behaves as a crystalloid when dissolved in water but
behaves as a colloid when dissolved in benzene.
(c) When solution is added to KI solution, the precipitated AgI
adsorbs I-ions from the dispersion medium and negatively charged
colloidal solution results.