Question

A certain weak base has a Kb of 8.50 × 10-7. What concentration of this base will produce a pH of 10.23?

Answer 1

PH = 10.23

POH =14-PH

         = 14-10.23

        = 3.77

POH   = 3.77

-log[OH-] = 3.77

    [OH-] = 10^-3.77    = 1.69*10^-4 M

[OH-] = Kb*C

1.69*10^-4   = 8.5*10^-7 *C

1.69*10^-4 * 1.69*10^-4    = 8.5*10^-7 *C

C                                = 1.69*10^-4 * 1.69*10^-4/ 8.5*10^-7

                                      = 3.36*10^-2 M