Question

find the pH of each of the following solutions of mixtures of acids: .125M in HBr and .130 M in HCHO2, .155M in HNO2 and 9.0*10^-2M in HNO3, 5.5×10−2 in acetic acid and 5.5×10−2 in hydrocyanic acid

Answer 1

For 1 and 2, calculate the H^+ from the strong acid first, use the H^+ from that calculation as a common ion to determine the H^+ from the weak acid, add them together (I suspect the weak acid will contribute so little it won't make much difference) for the total H^+. For the third one, follow the same procedure except now you are dealing with two weak acid BUT one is much stronger than the toher.