CHEM 1212 Exam 3 Review Presented by UGA’s Academic Resource Center 03/23/16 1

Chapter 16: Chemistry of Acids and Bases 2

Acid/Base Definitions 3

Boric acid (H 3 BO 3 ) is a weak monoprotic acid that yields H 3 O + ions in water. H 3 BO 3 might behave either as a Brønsted-Lowry acid or as a Lewis acid. a)Write a balanced equation for the reaction with water in which H 3 BO 3 behaves as a Brønsted-Lowry acid. b)Write a balanced equation for the reaction with water in which H 3 BO 3 behaves as a Lewis acid. Hint: one of the products contains a tetrahedral boron atom. 4

Autoionization of Water pH + pOH = pK w pH = -log[H 3 O + ] pOH = -log[ - OH] 10 -pH = [H 3 O + ] 10 -pOH = [ - OH] 5 What’s the rule for sigfigs with logarithms?

Equilibrium Constants for Acids & Bases AcidsBases 6 Stronger acid = larger K a = smaller pK a Stronger base = larger K b = smaller pK b

Acidic and Basic Salts NeutralBasicAcidic AnionsCl -, Br -, I -, NO 3 -, ClO 4 - CH 3 CO 2 -, HCO 2 -, CO 3 -, CN -, S 2-, F -, HS -, NO 2 -, HCO 3 -, PO 4 3-, SO 4 2-, HPO 4 2-, SO 3 2-, OCl - HSO 4 -, H 2 PO 4 -, HSO 3 - CationsNa +, Li +, Ca 2+, Ba 2+, K + [Al(H 2 O) 5 (OH)] 2+ [Al(H 2 O) 6 ] 3+, [Fe(H 2 O) 6 ] 3+, NH 4 + K a > K b then pH < 7 K a = K b then pH ≈ 7 K a 7 7

Predicting the Direction of Acid-Base Reactions 8 Conjugate acid/base pair

Using Equilibrium Constants 9 This approximation is valid: M A > 100 × K a

Break for Questions 10

Chapter 17: Buffers and other Aqueous Equilibria 11

Common Ion Effect 12 The presence of a common ion suppresses the dissociation of weak acids/bases. It will cause the reaction to proceed to the right to a lesser extent than without the presence of a common ion. The effect this has on the pH is called the “Common Ion Effect.”

Buffers A buffer solution consists of a weak acid and its conjugate base, or a weak base and its conjugate acid A buffer resists changes in pH when a strong acid/base is added 13

Buffers 14

Break for Questions 15