(A) How many grams of (NH₄)₂SO₄ must be dissolved in 0.500 L of 0.35 M NH₃ to produce a solution with pH = 9.00? (Assume that the solution volume remains at 0.500 L.)

(B) In Practice Example 17-3A, we established that an appropriate mixture of a strong acid and the salt of a weak acid is a buffer solution. Show that a solution made by adding 33.05 g NaCH₃COO · 3 H₂O(s) to 300 mL of 0.250 M HCl should have pH ≈ 5.1.

Practice Example 17-3A

Describe how a mixture of a strong acid (such as HCl) and the salt of a weak acid (such as NaCH₃COO) can result in a buffer solution.