How would you calculate the concentration of an aqueous solution of Ca(OH2)that has a pH of 12.57.

Answer 1

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

Ksp = (Ca^+2)(OH^-)^2
pH = 12.57. Convert to pOH, then to (OH^-). Substitute into Ksp and solve for (Ca^+2). That will be the concn of Ca(OH)2.