[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.

I sent this question a couple of days ago...I think I figured it out with the "hint" help but was wondering if someone could double check my answers?
Answer to a.)  pH = 3.65
Answer to b.) pH = 4.06

[jdurg]

Well, I did a very quick check here at work and the pH I came up with was 2.26.  However, this was done in about five seconds so I'll double-check the answer when I get home.  Just one thing you have to remember is that the initial concentration of H+ ions is greater than the concentration of HCOO- ions.  Therefore, the pH will be slightly lower than you may expect from just the HCOOH dissociation.