Question

What are the pH and pOH of a solution of 2.0 M HCl, which ionizes completely?

a) pH = 2, pOH = 12
b) pH = 12, pOH = 2
c) pH = 0.3, pOH = 13.7
d) pH = 13.7, pOH = 0.3

Answer 1

The pH and pOH of a 2.0 M HCl solution that ionizes completely are pH = 0.3 and pOH = 13.7, respectively.

Step-by-step explanation:

The question deals with the calculation of pH and pOH for a 2.0 M HCl solution which ionizes completely. Since HCl is a strong acid, it dissociates completely to form hydronium ions (H3O+) and chloride ions (Cl-).

The concentration of hydronium ions, [H3O+], equals the molarity of the HCl solution, which is 2.0 M. To find the pH, we take the negative logarithm (base 10) of the hydronium ion concentration:

pH = -log[H3O+] = -log(2.0) = 0.3

Since pH plus pOH must always equal 14 at 25 °C, we can find the pOH:

pOH = 14.00 - pH = 14.00 - 0.3 = 13.7

Therefore, the correct answer is c) pH = 0.3, pOH = 13.7.