At 2 5 ∘ C , K a of acetic acid and K b of ammonia are both 1.8 × 1 0 − 5 . Which of the following salts, dissolved in water, gives a solution of pH very close to 7?

Question

At 2 5 ∘ C , K a ​ of acetic acid and K b ​ of ammonia are both 1.8 × 1 0 − 5 . Which of the following salts, dissolved in water, gives a solution of pH very close to 7?

TestHub · Accepted Answer

For a salt of a weak acid and a weak base, $pH = 7 + \frac{1}{2} (p K_{a} - p K_{b})$ .

Here $p K_{a} = p K_{b}$ , so pH = 7: ammonium acetate.

$NH_{4} Cl$ is acidic, $CH_{3} COONa$ is basic and $NaHSO_{4}$ is acidic.

Answer: (C).

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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