ATB Question of the Day Day 1 4-19 0.108 The pH for a 0.10 M solution of a monoprotic acid is 1.2, what is the Ka? 0.108 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Assignment Day 1 4-19 page 669 #s 27-34  due Tuesday Day 5 4-17 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

III. Strong and Weak Acids and Bases Base Dissociation Constant – Kb Write the Keq for the dissociation of NH3(aq) above. *** for dilute aqueous solutions the concentration of water is a constant so, [NH4+] * [OH-] Keq = [NH3] * [H2O] Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

III. Strong and Weak Acids and Bases Base Dissociation Constant – Kb Or in general form:  the base dissociation constant (Kb) measures the extent to which a base dissociates in aqueous solution, and so can be used to represent the strength of a base. The stronger the base, the higher the Kb value. [conjugate acid] * [OH-] Kb = [base] Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

III. Strong and Weak Acids and Bases Differentiating Concentration and Strength: Strength refers to the extent of ionization or dissociation of an acid or base, while concentration indicates how much of a substance is dissolved.  Recall that substances can dissolve without dissociating (sugar). Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

III. Strong and Weak Acids and Bases Differentiating Concentration and Strength: *** Strength is independent of concentration and vice versa. Acidic Solution Molar Concentration Relative Concentration Relative Strength Hydrochloric acid 12 M HCl Concentrated Strong Gastric Juice (stomach acid) 0.08 M HCl Dilute Acetic acid 17 M CH3COOH Weak Vinegar 0.2 M CH3COOH Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

IV. Neutralization Reactions Acid-Base Reactions = Neutralization Reactions  In general acids and bases react to produce a salt (ionic substance) and water.  The complete reaction of a strong acid and a strong base produces a neutral solution – neutralization reaction. Example: HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l) Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

IV. Neutralization Reactions Acid-Base Reactions = Neutralization Reactions  Mole Ratios and Neutralization Reactions (example problem) How many moles of sulfuric acid are needed to neutralize 0.50 moles of sodium hydroxide? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Conjugate Acids and Bases Brønsted-Lowry Acids and Bases Conjugate Acids and Bases The figure below shows the reaction that takes place when sulfuric acid dissolves in water. The products are hydronium ions and hydrogen sulfate ions. Use the figure to identify the two conjugate acid-base pairs. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Acid-Base Definitions Interpret Data This table compares the definitions of acids and bases. Acid-Base Definitions Type Acid Base Arrhenius H+ producer OH– producer Brønsted-Lowry H+ donor H+ acceptor Lewis electron-pair acceptor electron-pair donor The Lewis definition is the broadest. It extends to compounds that the Brønsted-Lowry theory does not classify as acids and bases. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Identifying Lewis Acids and Bases Sample Problem 19.1 Identifying Lewis Acids and Bases Identify the Lewis acid and the Lewis base in this reaction between ammonia and boron trifluoride. NH3 + BF3 → NH3BF3 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Are hydrogen-ion donors also electron-pair acceptors? Yes. All substances defined as acids by the Brønsted-Lowry definition (an acid is a hydrogen-ion donor) are also defined as acids by the Lewis definition (an acid is an electron-pair acceptor). That means that these substances are both hydrogen-ion donors and electron-pair acceptors. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Key Concepts According to Arrhenius, acids are hydrogen-containing compounds that ionize to yield hydrogen ions in aqueous solution. Bases are compounds that ionize to yield hydroxide ions in aqueous solution. According to Brønsted-Lowry theory, an acid is a hydrogen-ion donor and a base is a hydrogen-ion acceptor. According to Lewis, an acid accepts a pair of electrons and a base donates a pair of electrons. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Glossary Terms hydronium ion (H3O+): the positive ion formed when a water molecule gains a hydrogen ion conjugate acid: the particle formed when a base gains a hydrogen ion; NH4+ is the conjugate acid of the base NH3 conjugate base: the particle that remains when an acid has donated a hydrogen ion; OH– is the conjugate base of the acid water Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

amphoteric: a substance that can act as both an acid and a base Glossary Terms conjugate acid-base pair: two substances that are related by the loss or gain of a single hydrogen ion; ammonia (NH3) and the ammonium ion (NH4+) are a conjugate acid- base pair amphoteric: a substance that can act as both an acid and a base Lewis acid: any substance that can accept a pair of electrons to form a covalent bond Lewis base: any substance that can donate a pair of electrons to form a covalent bond Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

BIG IDEA Reactions Chemists define acids and bases according to the ions they yield in aqueous solution. Chemists also define acids and bases based on whether they accept or donate hydrogen ions, and whether they are electron-pair donors or acceptors. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

[conjugate acid] * [OH-] Kb = [base] [NH4+] * [OH-] Kb = Keq * [H2O] = [NH3] [H3O+] * [CH3COO-] Ka = Keq * [H2O] = [CH3COOH] [conjugate acid] * [OH-] Kb = [base] Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

[NH4+] * [OH-] Keq = [NH3] * [H2O] Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.