[tabularasa]

A 1.50 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the solution after the addition of 0.0500 moles of solid NaOH. Assume no volume change upon the addition of base. The Ka for HF is 3.5 X 10^-4.

What I'm not entirely sure about is the solid NaOH because if you do an ICE chart for this equilibrium, solids and liquids are not expressed in the Ka problem (I think?). In order to get a pH, you have to take the negative log of the Ka.

The answer on my practice exam is 3.57 and I have no idea why this is the answer because my professor never mentioned anything about solids being added in.  Can someone please steer me in the right direction, because I'm totally lost. Thanks!

[AWK]

NaOH will react with HF.

[Borek]

Also note that buffer questions usually require use of Henderson-Hasselblach equation, not ICE table. This one doesn't look to be exception to this rule.