Question

What is the pH of 0.45M NaF?

pH=

Answer 1

Ka of HF = 6.3×10^–4

pKa of HF = 3.20

F- + H2O ----------------> HF + OH-

0.45                                     0         0

0.45 - x                               x          x

Kb = x^2 / 0.45 - x

1.587 x 10^-11 = x^2 / 0.45 - x

x = 2.67 x 10^-6

[OH-] = 2.67 x 10^-6 M

pOH = -log (2.67 x 10^-6 )

pOH = 5.57

pH = 8.43