Calculate the pH of the solution that results from the addition of 0.040 moles of HNO3 to a buffer made by combining 0.500 L of 0.380 M HC3H5O2 ( Ka = 1.30 x 10-5) and 0.500 L of 0.380 M NaC3H5O2. Assume addition of the nitric acid has no effect on volume.