Question

Use two concentration tables to calculate the concentrations of all species present in a 0.0774 M solution of KBrO. The K_a for HBrO is 2.8E-9.

What is the concentration of K⁺?

What is the concentration of BrO^-?

Answer 1

concnetration of KBrO = 0.0774 M

KBrO is a salt of strong base and weak acid. so pH > 7

BrO- +   H2O   --------------> HBrO + OH-

0.0774                                       0           0

0.0774 - x                                   x            x

pKa of HBrO = - log (2.8 x 10^-9) = 8.55

pH = 7 + 1/2 (pKa + log C)

     = 7 + 1/2 (8.55 + log 0.0774)

pH = 10.72

[H+] = 1.91 x 10^-11 M

[OH-] = 5.25 x 10^-4 M

[BrO-] = 0.0769 M

[K+] = 0.0774 M