Question

Calculate the pH of a mixture that contains 0.13 M of HCl and 0.23 M of HBrO.

Answer 1

first consider HCl

we know that

HCl is a very strong acid

HCl --> H+ + Cl-

as it is a strong acid

[H+] = [HCl] = 0.13

now

consider HBrO

we know that

HBrO is a weak acid

and for weak acids

[H+] = sqrt( Ka x C)

Ka for HBrO is 2.8 x 10-9

so

[H+] = sqrt ( 2.8 x 10-9 x 0.23)

[H+] = 2.5377 x 10-5

now

total [H+] = [H+] from HCl + [H+] from HBrO

so

total [H+] = 0.13 + ( 2.5377 x 10-5)

total [H+] = 0.130025377

now

we know that

pH = -log [H+]

so

pH = -log 0.130025377

pH = 0.886

so

pH of the solution is 0.886