What is the ph of a solution of 0.20 m hno2 containing 0.10 m nano2 at 25°c, given k a of hno2 is 4.5 * 10-4?

Question

Andres Pineda

Chemistry

9 July, 17:09

What is the ph of a solution of 0.20 m hno2 containing 0.10 m nano2 at 25°c, given k a of hno2 is 4.5 * 10-4?

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Answers (1)

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Bronson Noble · Answer 1

Answer is: pH of solution is 3.05.

c (HNO ₂) = 0.20 M.

c (NaNO ₂) = 0.10 M.

Ka (HNO ₂) = 4.5·10⁻⁴.

This is buffer solution, so use Henderson-Hasselbalch equation:

pH = pKa + log (c (NaNO ₂) : c (HNO₂)).

pH = - log (4.5·10 ⁻⁴) + log (0.10 M : 0.20 M).

pH = 3.35 - 0.30.

pH = 3.05.