The dissociation constant for CH3COOH is 1.8 × 10^–5 at 298 K. The electrode potential for the half- — Electrochemistry Chemistry Question
Question
The dissociation constant for CH3COOH is 1.8 × 10^–5 at 298 K. The electrode potential for the half-cell: Pt \| H2 (1 bar) \| 0.5 M – CH3COOH, at 298 K is (log 2 = 0.3; log 3 = 0.48; 2.303RT/F = 0.06)
Answer: D
💡 Solution & Explanation
$[H^+] = \sqrt{K_a \cdot C} = \sqrt{1.8 \times 10^{-5} \times 0.5} = \sqrt{9 \times 10^{-6}} = 3 \times 10^{-3}$ M. pH = $-\log(3 \times 10^{-3}) = 3 - \log 3 = 3 - 0.48 = 2.52$. The cell notation Pt \| H2 \| H+ represents an oxidation half-cell. Oxidation potential = $0.06 \times \text{pH} = 0.06 \times 2.52 = +0.1512$ V.
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