0.060 M 트리메틸아민(trimethylamine) 용액의 pH

0.060 M 트리메틸아민(trimethylamine) 용액의 pH

 

 

0.060 M 트라이메틸아민(trimethylamine) 용액의 pH와

(CH3)3N과 (CH3)3NH^+의 농도를 구하시오.

 

 

Find the pH and concentrations of (CH3)3N and (CH3)3NH^+

in a 0.060 M solution of trimethylamine. Kb = 6.3×10^(-5)

 

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................ (CH3)3N + H2O ⇌ (CH3)3NH^+ + OH^-

평형에서, ... 0.060-x ............. x ................ x

 

 

 

Kb = [(CH3)3NH^+][OH^-] / [(CH3)3N]

= x^2 / (0.060-x) = 6.3×10^(-5)

( 참고 https://ywpop.tistory.com/4294 )

 

 

 

0.060-x ≒ 0.060 이라 가정하면,

x = [0.060 × (6.3×10^(-5))]^(1/2) = 0.001944 M = [OH^-]

( 0.060×5% = 0.003 > 0.001944 이므로, 근사 가정 ok. )

 

 

 

pOH = -log[OH^-] = -log(0.001944) = 2.71

 

pH = 14.00 – pOH = 14.00 – 2.71 = 11.29

 

 

 

[(CH3)3N] = 0.060-x = 0.060 – 0.001944 = 0.058056 M

 

[(CH3)3NH^+] = 0.001944 M

 

 

 

답: pH = 11.29, [(CH3)3N] = 0.058 M, [(CH3)3NH^+] = 0.0019 M

 

 

 

[ 관련 예제 https://ywpop.tistory.com/5879 ] 0.05 M 트리메틸아민 용액의 pH

 

 

 

[키워드] 트리메틸아민 용액의 pH, trimethylamine 용액의 pH