Question

Calcium hydroxide, Ca(OH)2, is a dibasic compound, producing 2 moles of OH− for every mole of calcium hydroxide. If the pH of a calcium hydroxide solution is 10.52, what is the [OH−] in the solution and the initial [Ca(OH)2]. Hint: For dibasic ionic compounds, we assume that the compound dissociates completely in solution.

Answer 1

PH   = 10.52

POH   = 14-PH

           = 14-10.52

            = 3.48

POH   = 3.48

-log[OH^-]   = 3.48

   [OH^-]    = 10^-3.48   = 0.00033   = 3.3*10^-4M

Ca(OH)2(aq) ------------> Ca^2+ (aq) + 2OH^- (aq)

1.65*10^-4M                                         2*1.65*10^-4M

initial ocncentration of Ca(OH)2   = 1.65*10^-4 M