0.1 mole of acetic acid has been dissolved per dm3 of the solution , percentage ionization of acetic acid will be
Answers
Explanation:
Acetic acid or ethanoic acid is an organic weak acid with Ka = 1.8 x 10^-5.
Ka = 1.8 x 10^-5
pKa = -log Ka
pKa = -log 1.8 x 10^-5
pKa = -(log 1.8 + log 10^-5)
pKa = 4.74
In water, acetic acid undergoes ionization to form H+ and CH3COO- ions.
CH3COOH <===> H+ + CH3COO-
The degree of ionization of the acid to form equimolar of H+ and CH3COO- is very small. In this respect, let [H+] = [CH3COO-] = A mole. Since CH3COOH is a very weak acid, then the concentration of CH3COOH after ionization is practically the same with its original concentration i.e. 0.1 M →[HA] = 0.1 M.
To determine the value of A, use the following formula :
Ka = {[H+] x [CH3COO-]}/[CH3COOH]}Solve
Ka = [A] x [A] /[CH3COOH]
1.8 x 10^-5 = A^2/0.1
A^2 = 1.8 x 10^-5 x 0.1
A^2 = 1.8 x 10^-6
Solve…. giving
[A] = 1.34 x 10^-3 M
Then, the percentage of ionization of acetic acid can be calculated using :
= {[A]/[HA]} x 100 %
= {[1.34 x 10^-3]/[0.1]} x 100 %
= [1.34 x 10^-4] x 100 %
= 1.34 x 10^-2 % or 0.0134%.....
Answer: