Question

A solution containing 50.00 mL of 0.1800 M NH3 (Kb = 1.77 x 10-5)

You titrate this solution with 0.4100 M HCI.
Determine the pH of the solution under the following conditions:
(a) initially
(b) after the addition of 5.00 mL of HCI
(c) after the addition of a total volume of 12.50 mL HCI
(d) after the addition of a total volume of 25.00 mL of HCI
(e) after the addition of 26.00 mL of HCI

Answer 1

To determine the pH of a solution during a titration, we need to consider the reaction between the acid and the base. In this case, we are titrating NH3 (a weak base) with HCl (a strong acid).

Step-by-step explanation:

To determine the pH of a solution during a titration, we need to consider the reaction between the acid and the base. In this case, we are titrating NH3 (a weak base) with HCl (a strong acid). NH3 reacts with HCl to form NH4+ and Cl-. The NH4+ ion can act as a weak acid, so we need to consider the hydrolysis of NH4+ to determine the pH of the solution.

(a) Initially, before any HCl is added, the pH can be calculated using the Kb expression for NH3. (b) After the addition of 5.00 mL of HCl, we need to consider the hydrolysis of both NH3 and NH4+. (c-d) After adding a total volume of 12.50 mL and 25.00 mL of HCl, respectively, we need to consider the hydrolysis of NH4+ only. (e) After the addition of 26.00 mL of HCl, the pH will be determined by the excess of HCl, making the solution acidic.