Calculate the pH of a solution prepared by dissolving 0.150 mol of acetic acid and 0.300 mol of sodium acetate in water sufficient to yield 1.00 L of solution. The Ka of acetic acid is 1.76 ⋅ 10-5. Calculate the pH of a solution prepared by dissolving 0.150 mol of acetic acid and 0.300 mol of sodium acetate in water sufficient to yield 1.00 L of solution. The Ka of acetic acid is 1.76 10-5. 3.892 10.158 5.056 2.516 4.502

pH = 5.056

Explanation:

Acetic acid (CH₃COOH), is in equilibrium with water, thus:

CH₃COOH + H₂O ⇄ CH₃COO⁻ + H₃O⁺

From here, it is possible to obtain H-H equation to find pH of a solution:

pH = pka + log₁₀ [CH₃COO⁻] / [CH₃COOH]

Where molarity of acetic acid, [CH₃COOH], is 0.150mol / 1.00L = 0.150M and molarity of acetate ion, [CH₃COO⁻], is 0.300mol / 1.00L = 0.300M. pKa of the buffer is -log Ka: 4.754

Replacing:

pH = 4.754 + log₁₀ [0.300M] / [0.150M]

pH = 5.056

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