What is the ph of a 0.45 m solution of aniline (c6h5nh2) ? (pkb  9.40) ?

Question

Chemistry

Fabian Wong

4 October, 09:00

What is the ph of a 0.45 m solution of aniline (c6h5nh2) ? (pkb  9.40) ?

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Naima Burton · Answer 1

Answer is: pH of aniline is 9.13.

Chemical reaction: C ₆H₅NH₂ (aq) + H₂O (l) ⇌ C₆H₅NH₃⁺ (aq) + OH⁻ (aq).

pKb (C₆H₅NH₂) = 9.40.

Kb (C₆H₅NH₂) = 10∧ (-9.4) = 4·10⁻¹⁰.

c₀ (C₆H₅NH₂) = 0.45 M.

c (C₆H₅NH₃⁺) = c (OH⁻) = x.

c (C₆H₅NH₂) = 0.45 M - x.

Kb = c (C₆H₅NH₃⁺) · c (OH⁻) / c (C₆H₅NH₂).

4·10⁻¹⁰ = x² / (0.45 M - x).

Solve quadratic equation: x = c (OH⁻) = 0.0000134 M.

pOH = - log (0.0000134 M.) = 4.87.

pH = 14 - 4.87 = 9.13.