Question

Sally prepared a saturated solution of calcium hydroxide by dissolving excess solid in water. She told Emily that in this saturated solution, the amount of solid dissolves does not change, but ionic bonds continue to be broken. Is Sally clever?

a) Explain

b) Calcium hydroxide is an ionic compound. Write an equation for the equilibrium that exists between solid calcium hydroxide and its ions in solution?

c) What would be the effect of adding a concentrated solution of caustic soda (sodium hydroxide) solution to the equilibrium?

Answer 1

(b) In solution :-

Ca(OH)₂ --> Ca⁺²(aq) + 2 OH^- (aq)

At equilibrium K_sp = [Ca⁺²][OH^-]² {K_sp = solubility product}

(c) Effect of adding concentrated solution of caustic soda to solution at equilibrium

• Ca⁺² concentration steadily decreases with increase in concentration of NaOH.
• Product of [Ca]⁺²[OH]^- increases symmetrically as Base (conecntartion of OH^-) increases.

(a)Yes Sally is clever as when Calcium hydroxide is dissolved in water it's amount doesn't changes but it only gets split into Ca⁺² and OH^- ions.

Thank you, hope this answer will help.