How do I complete an ICE table for a solution of nitrous acid, HNO2, one of the acids associated with acid deposition?

Answer 1

Part of it depends upon what you know about the HNO2 and part on what you want to know. For example, for 0.1M HNO2, you want to know H^+, then
.......HNO2 ==> H^+ + NO2^-
I.......0.1......0......0
C.......-x.......x......x
E.......0.1-x....x......x

Then you substitute the E-line into the Ka expression and solve for x.