what is the pH?I will choose best answer for your help. :). Created by Martha. science-mathematics-en - chemistry-en

If a buffer solution is 0.240 M in a weak acid (Ka = 7.2 × 10-5) and 0.460 M in its conjugate base?

May 2021 2 171 Report

If a buffer solution is 0.240 M in a weak acid (Ka = 7.2 × 10-5) and 0.460 M in its conjugate base?

what is the pH?

I will choose best answer for your help. :)

The pH of a buffer solution can be calculated using the Henderson Hasselbalch equation:

pH = pKa + log Cb/Ca

where Cb and Ca are the concentrations of the conjugate base and conjugate acid.

We know that:

Ca = 0.240 M

Cb = 0.460 M

Ka = 7.2 × 10-5,

pKa = -logKa = -log(7.2 × 10-5) = 4.14

pH=4.14 + log(0.460/0.240) = 4.43

use the henderson-hasselbach equation: pH=pKa+log[acid]/[conjugate base]

pKa = -log(Ka) = -log(7.2e-5)=4.14

pH=4.14+log(0.240/.460)=3.86