Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10^-³ M hydronium ion. A)4.65 × 10^-12M B)2.15 × 10^-3M C)2.67 D)11.33

Question

Quizplus · Accepted Answer

Acetic acid is a weak acid, and can be represented by the equation:
CH3COOH + H2O ⇌ CH3COO- + H3O+

The acid dissociation constant (Ka) for acetic acid is 1.8 × 10^-5.
Using the equation for Ka, we can calculate the concentration of hydronium ion:
Ka = [CH3COO-][H3O+] / [CH3COOH]
1.8 × 10^-5 = (x)(2.15 × 10^-13) / (0.1 - x)
where x is the concentration of hydronium ion.
Simplifying and solving for x gives:
x = 1.5 × 10^-3 M

Using the pH equation, we can calculate the pH:
pH = -log[H3O+]
pH = -log(1.5 × 10^-3)
pH = 2.67

Therefore, the best choice is C.

Calculate the PH for an Aqueous Solution of Acetic Acid