Estimate the approximate `PK_a` of `0.5 M CH_3 COOH.` Degree of dissociation (ionization) is 0.15.
`(log 1.32 = 0.12)`

Options

A. `2.0`
B. `1.5`
C. `1.88`
D. `0.15`

Answer

C

Explanation

Given C = 0.5 m of `CH_3 COOH`
Degree of `(alpha) = 0.15`
`K_a = (c alpha^2)/(1 - alpha) = (0.5 xx (0.15)^2)/(1-0.15)= 0.0132`
`ph_a = - log (k_a)`
`= - log (0.0132)`
`pK_a = 1.879 ~~ 1.88`