Question

1) What is the pH of an aqueous solution that contains a hydronium ion concentration of 9.0 ✕ 10−4 M?

2) If the pOH of the solution is 12.33, determine the hydroxide ion concentration of the solution.

3) What is the pH of an aqueous solution with a pOH of 5.92 at 25°C?

Answer 1

1) given concentration of hydronium ion

[ H⁺] = 9.0 x 10^-4 M

Note: in this case concentration is greater then 10^-6 M, so that H⁺ ion coming from water can be neglected.

pH = - log [H⁺]

pH= - log [9.0 x 10^-4 ]

pH= -3 log 3 + 4 log 10

pH= - 1.431 + 4

pH= 2.587

2.) pOH = 12.33

pOH= - log [OH^-]

12.33 = -log [OH^- ]

or -12.33 = log [OH^-]

antilog -12.33 = [OH^-]

[OH-] = 4.67 x 10^-13

3.) At 25 degree centigrade

pH + pOH = 14

pH = 14 - 5.92

pH = 8.08