If ionisation constant of acetic acid is 1.8 . 10^(-5), at what concen

1.	If ionisation constant of acetic acid is 1.8 . 10^(-5), at what concentration will it be dissociated to 2%
Answer» At a concentration of 0.045[M], acetic ACID will be dissociated to 2% Acetic acid (CH₃COOH) dissociates into two IONS- CH₃COO⁻ and H⁺ CH₃COOH ⇄ CH₃COO⁻ + H⁺ Initial CONC.: c 0 0 At equillibrium: c(1-α) cα cα where α is the degree of dissociation = 2% = 2/100 = 0.02 Ionisation constant K = [(cα)(cα)]/[c(1-α)] = cα²/(1-α) = cα² [1-α≈1, as α is very SMALL] C = K/α² = (1.8×10⁻⁵)/(0.002)² = 0.045 [M] This is the required concentration.

If ionisation constant of acetic acid is 1.8 . 10^(-5), at what concentration will it be dissociated to 2%

Answer»

Acetic acid (CH₃COOH) dissociates into two IONS- CH₃COO⁻ and H⁺

CH₃COOH ⇄ CH₃COO⁻ + H⁺

Initial CONC.: c 0 0

At equillibrium: c(1-α) cα cα

where α is the degree of dissociation = 2% = 2/100 = 0.02

Ionisation constant K = [(cα)(cα)]/[c(1-α)] = cα²/(1-α) = cα² [1-α≈1, as α is very SMALL]

C = K/α² = (1.8×10⁻⁵)/(0.002)² = 0.045 [M]

This is the required concentration.