Calculate h3o + in an aqueous solution that is 0.10M NaNO2 and 0.055M HNO2

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Chemistry

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1 August, 11:12

Calculate h3o + in an aqueous solution that is 0.10M NaNO2 and 0.055M HNO2

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Leroy Cooke · Answer 1

Answer is: concentration of hydronium ions is 8.13·10⁻⁴ M.

c (HNO ₂) = 0.055 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 (0.055 M : 0.10 M).

pH = 3.35 - 0.26.

pH = 3.09.

[H₃O⁺ ] = 10 ∧ (-3.09).

[H₃O⁺] = 8.13·10⁻⁴ M.