Question

20 ml of a 1.0 m hcl solution are added to 3.0 l of acid solution with a ph of 5.35. the ph of the mixture rises to 5.33 was the initial 3.0 l solution a buffered solution?

Answer 1

You may suppose you have a 0.1 M solution of NH3, from:

NH4Cl + NaOH > NH3 + H2O.

Then you can compute the pH from the concentration of NH3 and its pKb.

The concentration is high enough to use the simplified formula:

[OH] = sqr(Kb*conc)