CHM 2046C Sample Module 12 Name: ________________

Part A. The Common-Ion and the Common-Ion Effect 10 points

1. What is a common-ion?

2. What would be the common ion for the following weak acids and weak bases and in addition to its formula give its name:

(a) Lactic Acid: CH₃CH(OH)COOH

(b) Acetic Acid: CH₃COOH

(c) Ammonia dissolved in Water: NH₃ in H₂O

3. What is the Common-Ion Effect for Weak acids, Weak base, or Salt Solubility?

Discuss Examples in General:

a)

b)

4. Does the pH of the solution increase, decrease, or stay the same when you:

(a) Add Ammonium nitrate to a dilute aqueous solution of ammonia?

(b) Add solid potassium acetate to a dilute aqueous solution of acetic acid?

(c) Add solid sodium lactate to a dilute aqueous solution of lactic acid?

(d) Add solid Potassium nitrate to a dilute solution of Potassium hydroxide?