Explain how to calculate the pH of the following solutions:

(a) A solution that is 0.25 M KOH and 1.00 M ammonia

(b) A solution that is 0.40 M HCl, 0.20 M HBr, 0.10 M HCOOH, and 0.20 M HF

(c) A solution that is 0.80 M HCOOH and 0.50 M HOCl

Strategy

If strong acids or bases are present, use their concentrations to calculate the pH. If a single weak acid or weak base dominates (is much stronger than the other weak acids or bases), calculate the pH based on its concentration, ignoring the weaker electrolytes.