"Calculating the pH of a Solution of a Weak Acid; Calculating the pH of the Solution after the Addition of Strong Base The Ka for formic acid is 1.78 × 10−4 M. a. What is the pH of a 0.1 M solution of formic acid? b. 150 mL of 0.1 M NaOH is added to 200 mL of 0.1 M formic acid, and water is added to give a final volume of 1 L. What is the pH of the final solution?"