Jodi is carrying an open container containing 0.05 moles of solid sodium acetate across the lab, but she trips and spills the contents of the container into a 1.0 L beaker of 0.1 M aqueous acid solution (at 298 K). Assuming that the addition of sodium acetate does not change the volume of the solution, what is the final pH of the mixture? (Ka for acute acid is 1.8 x 10^-5)
A) 11.3
B) 9.56
C) 4.44
D) 2.87
E) 6.76
A word problem on pH and Ka with mixtures? I think we're doing intro to buffers but I'm just not familiar with it at all?
2016-03-02 3:18 am
回答 (1)
2016-03-02 3:27 am
When the sodium acetate completely dissolves in the solution, [CH₃COO⁻] = 0.05 M
CH₃COOH(aq) + H₂O(l) ⇌ CH₃COO⁻ + H₃O⁺(aq)
pH = pKa - log([CH₃COOH]/[CH₃COO⁻]
pH = -log(1.8 × 10⁻⁵) - log(0.1/0.05)
pH = 4.44
...... The answer is (C).
CH₃COOH(aq) + H₂O(l) ⇌ CH₃COO⁻ + H₃O⁺(aq)
pH = pKa - log([CH₃COOH]/[CH₃COO⁻]
pH = -log(1.8 × 10⁻⁵) - log(0.1/0.05)
pH = 4.44
...... The answer is (C).
收錄日期: 2021-04-18 14:33:26
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