An aqueous solution containing 40.0 mL of 0.120 M ammonia, NH₃
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
An aqueous solution containing 40.0 mL of 0.120 M ammonia, NH₃, is titrated with 0.100 M HCl at 25 °C. The base-dissociation constant of ammonia is Kb = 1.8 × 10⁻⁵.
(a) After 24.0 mL of HCl have been added, calculate the millimoles of NH₃ and NH₄⁺ present in the mixture.
(b) Determine the pH of the solution at the 24.0 mL mark. Show all steps in your calculation.
(c) Suppose instead that 30.0 mL of HCl had been added. Without performing a full numerical calculation, state whether the pH would be greater than, less than, or equal to the value obtained in part (b). Briefly justify your answer based on the relative amounts of NH₃ and NH₄⁺ present.