CH3COOH′⇌CH3COO−+H+ Ka=[CH3COOH][CH3COO−][H+]
Given that, [CH3COO−]=[H+]=3.4×10−4M Ka for CH3COOH=1.7×10−5 CH3COOH is weak acid, so in it [CH3COOH] is equal to initial concentration. Hence, 1.7×10−6=[CH3COOH](3.4×10−4)(3.4×10−4) [CH3COOH]=1.7×10−53.4×10−4×3.4×10−4 =6.8×10−3M