Answer
See explanation below.
Work Step by Step
1
(A) Given :
1. pH of the buffer = 4.39
2. Ka of Acid (CH3COOH) = 1.8 x 10^-5
2
(B) Formulae :
1. Henderson - Hasselbalch equation of a buffer : pH = pKa + log [base] / [acid]
2. pKa = -log(Ka)
3
(C) Solution :
1. pKa = -log (Ka)
= -log (1.8 x 10^-5)
= 4.74 .... (1)
2. pH = pKa + log [base] / [acid]
4.39 = 4.74 + log ([CH3COO-] / [CH3COOH])
-0.35 = log ([CH3COO-] / [CH3COOH])
[CH3COO-] / [CH3COOH] = 10^(-0.35) = 0.45
Hence, the component concentration ratio [CH3COO-] / [CH3COOH] is equal to 0.45