Question

What is the (H3O+) and

the ph of a buffer that consists of 0.25M HNO2 and 0.69M KNO2?

(Ka of HNO2 = 7.1 x 10^-4)

is this right?
pH of acidic buffer

pH = pka + log(salt/acid)

pka = -log ka = -log(7.1*10^(-4)) = 3.15

= 3.15+log(0.25/0.69)

pH = 2.71

[H3O+] = 10^-pH = 10^(-2.71) = 0.001945 M
Thank you.

Answer 1

In the HH equation didn't you say it was salt/acid. KNO2 is the salt; HNO2 is the acid.

Answer 2

[base] > [acid] so your pH should be larger than pka. check DrBob's answer :)