Pyridine (c5h5n) is a particularly foul-smelling substance used in manufacturing pesticides and plastic resins. calculate the ph of a 0.115 m solution of pyridine (kb = 1.4*10-9).

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Chemistry

Taylor

19 December, 06:05

Pyridine (c5h5n) is a particularly foul-smelling substance used in manufacturing pesticides and plastic resins. calculate the ph of a 0.115 m solution of pyridine (kb = 1.4*10-9).

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Emely Bradford · Answer 1

Answer is: ph value of pyridine solution is 9.1.

Chemical reaction: C₅H₅N + H₂O → C₅H₅NH⁺ + OH⁻.

c (pyridine - C ₅H₅N) = 0.115M.

Kb (C ₅H₅N) = 1.4·10⁻⁹.

[C₅H₅NH⁺] = [OH⁻] = x; equilibrium concentration.

[ C₅H₅N] = 0.115 M - x.

Kb = [C₅H₅NH⁺] · [OH⁻] / [C₅H₅N].

1.4·10⁻⁹ = x² / (0.115 M - x)

Solve quadratic equation: x = [OH⁻] = 0.0000127 M.

pOH = - log (0.0000127 M) = 4.9

pH = 14 - 4.9 = 9.1.