A saturated solution of calcium hydroxide, Ca(OH)₂, is in contact with excess solid Ca(OH)₂. Which of the following statements correctly describes what will happen when aqueous HCl (a strong acid) is added to this mixture, and system returns to equilibrium? (For Ca(OH)₂, K_sp = 6.5 * 10¯⁶) A) The solubility of Ca(OH)₂ will be unchanged. B) The OH¯ concentration will decrease and the Ca²⁺ concentration will increase. C) The OH¯ concentration will increase and the Ca²⁺ concentration will decrease. D) The concentrations of both Ca²⁺ and OH¯ will increase. E) The solubility of Ca(OH)₂ will decrease.

Question

Quizplus · Accepted Answer

When HCl is added to the saturated solution of Ca(OH)2, it will react with the OH- ions present in the solution, according to the following equation:

H+ + OH- → H2O

This reaction will shift the equilibrium to the left, causing the concentration of OH- ions to decrease. At the same time, according to Le Chatelier's principle, the decrease in OH- concentration will cause the dissolution of Ca(OH)2 to increase in order to compensate for the loss of OH-. Therefore, the concentration of Ca2+ ions will increase in the solution.

Thus, option B is the correct answer as it correctly predicts that the OH- concentration will decrease and the Ca2+ concentration will increase in the solution.

A Saturated Solution of Calcium Hydroxide, Ca(OH)2, Is in Contact

A Saturated Solution of Calcium Hydroxide, Ca(OH)₂, Is in Contact