pH가 4.0인 아세트산 용액의 몰농도

pH가 4.0인 아세트산 용액의 몰농도

 

 

Acetic acid is added to water until the pH value reaches 4.0.

What is the total concentration of the added acetic acid?

 

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> CH3COOH의 Ka = 1.8×10^(-5)

( 문헌값 )

 

 

 

pH = –log[H^+] = 4.0

 

[H^+] = 10^(-4.0) M = x

 

 

 

CH3COOH(aq) ⇌ H^+(aq) + CH3COO^-(aq)

Ka = [H^+][CH3COO^-] / [CH3COOH]

 

Ka = (x)(x) / (C–x)

( 참고 https://ywpop.tistory.com/4294 )

 

 

 

C–x = x^2 / Ka

 

C = (x^2 / Ka) + x

= [ (10^(-4.0))^2 / (1.8×10^(-5)) ] + (10^(-4.0))

= 0.00066 M

= 6.6×10^(-4) M

 

 

 

답: 6.6×10^(-4) M