If 15.0 mL of 1.2e-4 mol/L HI is added to 26.0 mL of 9.2e-4 mol/L HI, what is the pH of the solution?
M x L = mols.
Calculate mols for solution 1, do the same for solution 2, add mols together and divide by total liters. That will be the new molarity. Then pH = -log(Molarity)