What is the ph of 0.11 m diethylamine, (ch3ch2) 2nh, (kb = 8.6 * 10-4) ?

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Chemistry

Alanna Cook

21 January, 17:26

What is the ph of 0.11 m diethylamine, (ch3ch2) 2nh, (kb = 8.6 * 10-4) ?

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Seamus Briggs · Answer 1

Answer is: pH value of diethylamine is 11,96.

Chemical reaction: (CH ₃CH₂) ₂NH + H₂O → (CH₃CH₂) ₂NH₂⁺ + OH⁻.

Kb ((CH₃CH₂) ₂NH) = 8,6·10⁻⁴.

c ((CH₃CH₂) ₂NH) = 0,11 M.

Kb ((CH ₃) ₂NH) = c (OH⁻) · c ((CH₃) ₂NH₂⁺) : c ((CH₃) ₂NH).

c (OH ⁻) = c ((CH₃CH₂) ₂NH₂⁺) = x.

8,6·10 ⁻⁴ = x² : (0,11 - x).

Solve quadratic equation: x = c (OH⁻) = 0,0092 M.

pOH = - log (0,0092 M) = 2,04.

pH = 14 - 2,04 = 11,96.