Question

What will be the solubility of the $Ca{(OH)_2}$solution when $NaOH$ is dissolved in it, compared with that in pure water?
A. Unaffected
B. Increased
C. Decreased
D. None

Answer 1

Hint: If you've got a solution and solute in equilibrium, including a common ion (an ion that is common with the dissolving solid) decreases the solubility of the solute. This is due to the fact Le Chatelier's precept states the response will shift closer to the left (in the direction of the reactants) to relieve the pressure of the extra product

Complete Step by step solution:
The solubility of $Ca{(OH)_2}$solution is reduced wherein $NaOH$ is dissolved, as compared with that in pure water due to the common ion effect. The hydroxide ion is a common ion.
The dissolution of $NaOH$ to a solution of $Ca{(OH)_2}$will lower the solubility of $Ca{(OH)_2}$. $Ca{(OH)_2}$ is sparingly soluble salt.
The dissociation of $Ca{(OH)_2}$in solution is represented by following solubility equilibrium.
$Ca{(OH)_2}(s) \to C{a^{ + 2}}(aq) + 2O{H^ - }(aq)$
$NaOH$ is a strong electrolyte and completely dissociates in aqueous solution.
$NaOH(s) \to N{a^ + }(aq) + O{H^ - }(aq)$
The dissociation of hydroxide ions which are common to $Ca{(OH)_2}$ . This suppresses the dissociation of $Ca{(OH)_2}$ .

So the correct answer is C.

Additional information:
Solubility is an belongings regarding the ability for a given substance, the solute, to dissolve in a solvent. It is measured in terms of the most quantity of solute dissolved in a solvent at equilibrium. The ensuing solution is referred to as a saturated solution.

Note:
Common Ion Effect on Solubility Adding a common ion decreases solubility, as the reaction shifts in the direction of the left to alleviate the strain of the excess product. Adding a commonplace ion to a dissociation reaction reasons the equilibrium to shift left, closer to the reactants, causing precipitation.