Question

The pka of acetic acid (CH3COOH) is

Answer 1

Answer:

pH of buffer with HOAc/OAc Ratio of 10/12 => 3.97

Explanation:

Given HOAc/OAc⁻ buffer with 10:12 acid to salt ratio;

Ka (HOAc) = 1.8 x 10⁻⁵

pKa (HOAc) = -log(Ka) = -log(1.8 x 10⁻⁵) =  4.75 ~ 4.8

Use Henderson-Hasselbalch equation => pH = pKa - log [base]/[acid])

=>  pH = 4.75 - log (10/12) = 4.8 - 0.83 =  3.97*

*closest answer to 3.97 is pH = 3.8