What is the ph of a 0.015 m aqueous solution of hydrazoic acid (hn3) (ka = 1.9 x 10â€"5) at 25Â°c?

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Chemistry

Maverick

6 September, 18:49

What is the ph of a 0.015 m aqueous solution of hydrazoic acid (hn3) (ka = 1.9 x 10â€"5) at 25Â°c?

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Anna Rollins · Answer 1

Answer is: pH value of aqueous solution of hydrazoic acid is 4,72.

Chemical reaction: N₃H + H₂O ⇄ N₃⁻ + H₃O⁺.

c (N₃H) = 0,015 M.

Ka (N₃H) = 1,9·10⁻⁵.

[ N₃⁻] = [H₃O⁺] = x.

[ N₃H) ] = 0,015 M - x.

Ka = [ N₃⁻] · [H₃O⁺] / [N₃H].

1,9·10⁻⁵ = x² / 0,015 M - x.

Solve quadratic equation: x = [H₃O⁺] = 0,000019 M.

pH = - log [H₃O⁺] = 4,72.