Acid Base PH, POH

Question

A solution contains 0.00568 M HCl. Determine the [H3O^+] for the solution.

Determine the [OH^−].

Determine the pH value for the solution.

Answer 1

Since HCl is a strong acid, we know that it will dissociate completely.

HCl + H₂O --> H₃O⁺ + Cl^-

Therefore:

[HCl] = [H₃O⁺] =0.00568M

Two equations we can use to solve the rest of the questions are:

(1) [H₃O⁺][OH^-] = K_W = 1*10^-14

(2) pH = -log[H₃O⁺]

To determine [OH], we can use equation (1) and rearrange to solve.

∴[OH] = (1*10^-14)/0.00568

[OH] = 1.76*10^-12

To find pH, we use equation (2):

pH = -log(0.00568)

∴pH = 2.25