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Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca(OH)2. It exists as a colourless crystal or white powder and is obtained when calcium oxide (called lime or quicklime) is mixed, or “slaked” with water. It is of low toxicity and enjoys many applications.
Let’s check out a typical exam-based question on Solubility Product under the topic of Equilibria, that has to do with calcium hydroxide.
Question:
(a) Write an expression for the solubility product, Ksp, of calcium hydroxide, Ca(OH)2.
(b) In a titration experiment in the school chemistry laboratory, 20.0 cm3 of an aqueous calcium hydroxide solution is completely neutralised by 18.2 cm3 of hydrochloric acid solution with a molar concentration of 0.050 moldm-3.
(i) Determine the hydroxide ion concentration, and hence the pH of the aqueous calcium hydroxide solution.
(ii) Calculate a value of the solubility product of calcium hydroxide, indicating its units.
(c) State one use of calcium hydroxide which depends on its solubility in water.
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