NCERT Class XI Chemistry Equilibrium Solutions

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Question : 46
Total: 73
The ionization constant of acetic acid is 1.74 × 105. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ions in the solution and its pH.
Solution:  
α =
Ka
C
=
1.74×105
5×102
= 0.0186
CH3COOHCH3COO+H+
Ka =
[CH3COO][H+]
[CH3COOH]
=
[H+]2
[CH3COOH]

or, [H+] = Ka[CH3COOH] = (1.74×105)(5×102) = 9.33 × 104M
[CH3COO] = [H+] = 9.33 × 104M
pH = - log (9.33 × 104) = 4 - 0.9699 = 4 - 0.97 = 3.03
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