Determine the pH of a 0.232 M Mg(OH)₂ solution at 25°C. A) 12.73 B) 13.37 C) 13.67 D) 0.333 E) 0.634

Question

Quizplus · Accepted Answer

Mg(OH)2 is a strong base which dissociates completely in water according to the equation: 
Mg(OH)2 (s) → Mg2+ (aq) + 2 OH- (aq)
The concentration of OH- can be calculated using the molarity of Mg(OH)2: 
[OH-] = 2 × 0.232 M = 0.464 M
Using the equation for the ion product constant of water:
Kw = [H+][OH-] = 1.0 × 10^-14 
pH can be calculated as:
pH = 14 - pOH = 14 - (-log[OH-]) = 14 - (-log 0.464) = 13.67

Determine the PH of a 0