The equivalent conductance of CH3COONa, HCl and NaCl at infinite dilution are 91,426 and 126 S cm3 eq−1 respectively at 25oC. The equivalent conductance of 1 M CH3COOH solution is 19.55 S cm2 eq−1. The pH of the solution is:
λoCH3COONa=λoCH3COO−+λoNa=91 Scm2eq−1.....(i)
λoHCl=λoH+λoCl−=426 Scm2eq−1.....(ii)
λoNaCl=λoNa+λoCl−=126 Scm2eq−1.....(iii)
λoCH3COOH=λoCH3COO−+λoH+=(i)+(ii)–(iii)=391 Scm2eq−1
λCH3COOH=19.5 Scm2eq−1 (given)
Degree of dissociation =λmλom=19.55391=0.05
CH3COOH⟶CH3COO−+H+
1(1−0.05) 0.05 0.05
[H+]=0.05 M
pH=−log[H+]=1.3