Hydrazoic acid has a chemical formula of HN3. It is a volatile and toxic acid with a Ka value of 2.5 X 10^-5.
Although it might not be the best choice, a student prepares a buffer using HN3 and NaN3 solutions. Find the approximate pH of the solution s/he made by mixing 0.150L of 0.800M HN3 with 0.200L of 0.25 M N3^- (the sodium ion is omitted for clarity).