A weak monobasic acid is 4 % dissociated in 0.05 M solution. What is percent dissociation in 0.1 M solution ?

Step-by-step solution

For a weak monobasic acid, the dissociation constant K_a is given by Ostwald's dilution law: K_a = C ^2 where C is the concentration and is the degree of dissociation. Given C₁ = 0.05 M and ₁ = 4 % = 0.04 : K_a = 0.05 (0.04)^2 = 0.05 0.0016 = 8 10⁻⁵ For the new concentration C₂ = 0.1 M, let the degree of dissociation be ₂ : K_a = C₂ ₂^2 8 10⁻⁵ = 0.1 ₂^2 ₂^2 = 8 10⁻⁵ 0.1 = 8 10⁻⁴ ₂ = 8 10⁻⁴ = 2.828 10⁻² The percent dissociation in 0.1 M solution is 2.828 % . Answer: 2.828 %