Calculate the ph of a 0.25M solution of monochloroacetic acid at 25 c

Question

Shaniya Grant

Chemistry

30 June, 17:08

Calculate the ph of a 0.25M solution of monochloroacetic acid at 25 c

+2

Answers (1)

Know the Answer?

Beckham Estrada · Answer 1

I think ... I'm only in 6th grade so I'm not really sure sorry.

Explanation:

You need to determine the concentration of H+. Acetic acid is a weak acid so you need to use the Ka of acetic acid. Remember Ka = [A-]*[H+]/[HA]. In the case of a weak acid [A-]=[H+] And we can approximate that change in [HA] is negligible. If we use the Ka of acetic acid as 1.75 X 10^-5 then the equation becomes:

1.75 X 10^-5 = [H+]2/[HA] substitute 0.25 M for [HA] and solve for [H+]. We get

[H+]=2.092X10^-3 pH is the - log [H+] so pH=2.68.