What is the pH of 0.010 M dimethylammonium nitrate?

What is the pH of 0.010 M dimethylammonium nitrate?

 

 

0.010 M 질산 다이메틸암모늄 용액의 pH는 얼마인가?

 

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▶ 참고: NH4NO3 용액의 pH를 구하는 문제와 100% 동일

[ https://ywpop.tistory.com/8564 ]

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dimethylammonium nitrate, (CH3)2NH2NO3

(CH3)2NH2NO3(aq) → (CH3)2NH2^+(aq) + NO3^-(aq)

 

 

 

(CH3)2NH2^+는 약염기인 (CH3)2NH의 짝산

---> 약염기의 짝산은 비교적 강한 산

---> 물과 가수분해 반응

(CH3)2NH2^+(aq) + H2O(l) ⇌ (CH3)2NH(aq) + H3O^+(aq)

Kh = Ka = Kw / Kb

( 참고 https://ywpop.tistory.com/5502 )

 

 

 

dimethylamine, (CH3)2NH의 Kb = 5.90×10^(-4)

 

 

 

Ka = (1.00×10^(-14)) / (5.90×10^(-4))

= 1.6949×10^(-11)

 

 

 

Ka = x^2 / (C–x)

( 참고 https://ywpop.tistory.com/4294 )

 

x = [Ka × C]^(1/2)

= [(1.6949×10^(-11)) × 0.010]^(1/2)

= 4.1169×10^(-7) M = [H3O^+]

 

 

 

pH = –log[H3O^+]

= –log(4.1169×10^(-7))

= 6.3854

 

 

 

답: pH = 6.4

 

 

 

 

[키워드] 0.010 M dimethylammonium nitrate pH