Calculate the pH of a 0.39 M CH3COOLi solution. Ka for acetic acid= 1.8 x 10^-5
CH3COOLi is a strong salt, So it dissociates completely
CH3COOLi CH3COO- + Li+
Now,
CH3COO- + H2O CH3COOH + OH-
Ka for acetic acid= 1.8 x 10-5
Kb = Kw/Ka = 1 x 10-14 / 1.8 x 10-5 =5.6 x 10-10
But,
Kb = [CH3COOH] [OH- ] / [CH3COO-]
5.6 x 10-10 = x2 / (0.39 - x )
5.6 x 10-10 = x2 / 0.39 (Neglecting x term from denominator since x << 0.39)
x2 = 2.184 x 10-10
x = 1.48 x 10-5
[OH-] = x = 1.48 x 10-5 M
pOH = - log [OH-] = -log(1.48 x 10-5) = 4.83
pH + pOH =14
pH = 14 - pOH = 14 - 4.83 = 9.17
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