I have to find the pH of a 8.57x10-10M HNO3 solution.
HNO3 + H20 <--> H3O+ + NO3-
The Attempt at a Solution
my theory was that the hydronium ion concentration would be the hydronium ion concentration in water (1x10-14 M) plus the concentration of the nitric acid (8.57x10-10 M... because it fully dissociates). then take the negative log of it. i came up with a pH of 6.99
but my chemistry professor told me that i did it wrong and it is actually more complicated and could involve equilibrium. what did i do wrong?