Modern Chemistry Chapter 15 Acid-Base Titration and pH Sections 1 & 2 Aqueous Solutions and the Concept of pH Determining pH and Titrations Chapter 15 Sec 1 The Concept of pH p. 499-510

Aqueous Solutions and the Concept of pH Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Chapter 15 Vocabulary Self Ionization pH pOH Acid-base indicator Transition interval Titration Equivalence Point Endpoint Standard Solution Primary Standard Standardization Chapter 15 Sec 1 The Concept of pH p. 499-510

Self Ionization of Water Two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton. Water is a weak electrolyte. H2O(l) + H2O(l)  H3O+(aq) + OH-(aq) At 25C: [H3O+] = [OH-] = 1.0 x 10-7 M Chapter 15 Sec 1 The Concept of pH p. 499-510

Self Ionization of Water BASE ACID ACID BASE [H3O+] = 1x10-7M [OH-] = 1x10-7M p.499 Chapter 15 Sec 1 The Concept of pH p. 499-510

Ionization Constant for H2O H2O(l) + H2O(l)  H3O+(aq) + OH-(aq) The Keq for water = Kw = [H3O+] [OH-] 1 Kw = [H3O+] [OH-] = 1.0 x 10-14 at 25C This is the ionization constant for water. Chapter 15 Sec 1 The Concept of pH p. 499-510

H3O+ and OH- BASIC [H3O+] < [OH-] NEUTRAL [H3O+] = [OH-] ACIDIC [H3O+] > [OH-] H3O+ OH- H3O+ OH- OH- H3O+ Chapter 15 Sec 1 The Concept of pH p. 499-510

Calculating [H3O+] [OH-] If [H3O+] is known then use 1.0 x 10-14 = [H3O+] [OH-] to get [OH-]. This works for strong and weak acids. Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Concentrations & Kw Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Sample Problems p.502 A 1.0 x 10–4 M solution of HNO3 has been prepared for a laboratory experiment. Calculate the [H3O+] of this solution. Calculate the [OH–]. a. 1.0 × 10−4 M H3O+ b. 1.0 × 10−10 M OH- Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Practice Problems p.502 1. Determine the hydronium and hydroxide ion concentrations in a solution that is 1 × 10−4 M HCl. 2. Determine the hydronium and hydroxide ion concentrations in a solution that is 1.0 × 10−3 M HNO3. [H3O+] = 1 × 10−4 M; [OH−] = 1 × 10−10 M [H3O+] = 1.0 × 10−3 M;[OH−] = 1.0 × 10−11 M Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Practice Problems p.502 3. Determine the hydronium and hydroxide ion concentrations in a solution that is 3.0 × 10−2 M NaOH. 4. Determine the hydronium and hydroxide ion concentrations in a solution that is 1.0 × 10−4 M Ca(OH)2. [H3O+] = 3.3 × 10−13 M;[OH−] = 3.0 × 10−2 M [H3O+] = 5.0 × 10−11 M;[OH−] = 2.0 × 10−4 M Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 The pH Scale pH – the negative of the common log of the hydronium ion concentration Based on the hydrogen ion concentration. Pouvoir hydrogéne (french) : hydrogen power Scale of 0-14 <7 Acidic =7 Neutral >7Basic Chapter 15 Sec 1 The Concept of pH p. 499-510

pH = -log [H3O+] The pH Scale log 1.0 x 10 =  What is the pH if [H3O+]= 1.0 x 10-12? log 1.0 x 10-12 = -12 - log 1.0 x 10-12 = 12 Chapter 15 Sec 1 The Concept of pH p. 499-510

Relationship of [H3O+] to [OH-] and pH Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 The pH Scale pH = -log [H3O+] If 1.00 x 10-14 = [H3O+] [OH-] what is the highest that [H3O+] can be? 1 x 10 0 pH=0 What is the lowest that [H3O+] can be? 1 x 10 -14 pH=14 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 pH Scale p. 503 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 The pH Scale Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 pH of Common Materials p. 504 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 pH of Common Materials p. 512 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 pH = 4 = -log [H3O+]  pH = -log [2.3x10-8]   [EE]  Using Your Calculator Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Sample Problems p.505 What is the pH of a 1.0 x 10–3 M NaOH solution? 11.00 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Practice Problems p.505 Determine the pH of the following solutions: a. 1 × 10−3 M HCl b. 1.0 × 10−5 M HNO3 c. 1 × 10−4 M NaOH d. 1.0 × 10−2 M KOH a. pH = 3.0 b. pH = 5.00 c. pH = 10.0 d. pH = 12.00 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Sample Problems p.506 What is the pH of a solution if the [H3O+] is 3.4 x 10–5 M? 4.47 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Practice Problems p.506 1. What is the pH of a solution if the [H3O+] is 6.7 × 10−4 M? 2. What is the pH of a solution with a hydronium ion concentration of 2.5 × 10−2 M? 3. Determine the pH of a 2.5 × 10−6 M HNO3 solution. 4. Determine the pH of a 2.0 × 10−2 M Sr(OH)2 solution. 1. pH = 3.17 2. pH = 1.60 3. pH = 5.60 4. pH = 12.60 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Sample Problems p.507 Determine the hydronium ion concentration of an aqueous solution that has a pH of 4.0. [H3O+] = 1 × 10−4 M Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Practice Problems p.508 1. The pH of a solution is determined to be 5.0.What is the hydronium ion concentration of this solution? 2. The pH of a solution is determined to be 12.0.What is the hydronium ion concentration of this solution? [H3O+] = 1 × 10−5 M [H3O+] = 1 × 10−12 M Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Practice Problems p.508 3. The pH of an aqueous solution is measured as 1.50. Calculate the [H3O+] and the [OH−]. 4. The pH of an aqueous solution is 3.67. Determine [H3O+]. [H3O+] = 3.2 × 10−2 M; [OH−] = 3.2 × 10−13 M [H3O+] = 2.1 × 10−4 M Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 pOH A scale based on the hydroxide ion concentration 0-14 <7 basic =7 neutral >7 acidic Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 pOH and Hydroxide Chapter 15 Sec 1 The Concept of pH p. 499-510

[H3O+] for Strong & Weak Acids For Strong Acids HCl  H+ + Cl- 0.10M 0.10M 0.10M Use the mole ratio. REVIEW For Weak Acids HF  H+ + F- 0.10M <0.10M <0.10M Use the “I.C.E.” or use equilibrium concentrations. Chapter 15 Sec 1 The Concept of pH p. 499-510

Calculating [H3O+] [OH-] Ka= [negative ion] [H3O+] [acid molarity] Ka Kw Kw = 1.00 x 10-14 = [H3O+] [OH-] pH = -log [H3O+] pH Chapter 15 Sec 1 The Concept of pH p. 499-510

Calculating [H3O+] [OH-] Ka [H3O+] . pH Kw Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Weak Acid Problems Assume that enough lactic acid, CH3CHOHCOOH, is dissolved in sour milk to give a solution concentration of 0.10 M lactic acid. A pH meter show that the pH of the sour milk is 2.43. Calculate the Ka for the equilibrium system. CH3CHOHCOOH  CH3CHOHCOO- + H+ 1.44 x 10-4 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Weak Acid Problems When the [HNO2] is 0.08M, the pH of the acid is 2.4 Calculate the Ka for the nitrous acid. HNO2+H2OH3O+ + NO2- 2.1 x 10-4 Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Acid & Base Strength Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Ch 15 Sec 1 Homework Calculating [H3O+], [OH-], Ka & pH Worksheet Chapter 15 Sec 1 The Concept of pH p. 499-510

Antacids & Neutralization Chapter 15 Sec 1 The Concept of pH p. 499-510

Chapter 15 Sec 1 The Concept of pH p. 499-510 Ch 15 Sec 1 Homework Page 509 # 1-6 Chapter 15 Sec 1 The Concept of pH p. 499-510