[Jen]

A buffer is prepared by adding 50.0 mL of 0.15 M HNO3(aq) to 100.0 mL of 0.12 M NaHCOO(aq) (sodium formate).

a.) calculate the pH of the buffer solution
b.) calculate the pH of the solution after 0.0020 mol of solid NaOH is added to the solution. Neglect any volume changes.

Is it possible to have HNO3 in a buffer solution since it is a strong acid and 100% ionized?  If so, then how would you calculate a.) and b.)?
If not, can you still calculate a.) and b.)?  I thought a buffer solution needed a conjugate acid and base?  These are not?!

[jdurg]

Here's one little hint.  The addition of the fully ionized nitric acid will cause a bunch of H+ ions to exist in solution.  The addition of NaHCOO, a weak acid's conjugate base, will cause a bunch of HCOO- ions to form in solution.  The buffer will exist because HCOO- will react with H+ to form HCOOH which is a weak acid and isn't going to fully ionize.