What is [h3o ] in a solution of 0.075 m hno2 and 0.030 m nano2?

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Ruby Weiss

Chemistry

31 January, 10:14

What is [h3o ] in a solution of 0.075 m hno2 and 0.030 m nano2?

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Rebekah · Answer 1

Answer is: concentration of hydrogenium ions is 9,54·10⁻⁵ M.

c (HNO₂) = 0,075 M.

c (NaNO₂) = 0,035 M.

Ka (HNO₂) = 4,5·10⁻⁵.

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

pH = pKa + log (c (NaNO₂) : c (HNO₂)).

pH = - log (4,5·10⁻⁵) + log (0,035 M : 0,075 M).

pH = 4,35 - 0,33.

pH = 4,02.

[H ₃O⁺] = 10∧ (-4,02).

[H ₃O⁺] = 0,0000954 M = 9,54·10⁻⁵ M.