4 Test Yourself A neutral aqueous solution A. has a 7.0 M H3O+ concentration.B. contains neither hydronium ions nor hydroxide ions.C. has an equal number of hydronium ions and hydroxide ions.D. None of the above
5 Kw – Ionization Constant for Water In pure water at 25 oC:[H3O+] = 1 x 10-7 mol/L[OH-] = 1 x 10-7 mol/LKw is a constant at 25 oC:Kw = [H3O+][OH-]Kw = (1 x 10-7)(1 x 10-7) = 1 x 10-14
8 The strength of a base depends on the extent it dissociates The strength of a base depends on the extent it dissociates. 1 mol mol mol
9 Calculating [H3O+] and [OH–] Hydronium Ions and Hydroxide IonsCalculating [H3O+] and [OH–]Strong acids and bases are considered completely ionized or dissociated in weak aqueous solutions.1 mol mol mol1.0 × 10−2 M NaOH solution has an [OH−] of 1.0 × 10−2 MThe [H3O+] of this solution is calculated using Kw.Kw = [H3O+][OH−] = 1.0 × 10−14
10 [H3O+][OH−] = 1.0 × 10−14 1 mol 1 mol 1 mol 1 mol Sample Problem A 1.0 X 10–4 M solution of HNO3 has been prepared for a laboratory experiment.a. Calculate the [H3O+] of this solution. (IONIZES COMPLETELY)b. Calculate the [OH–].1 mol mol mol mol[H3O+][OH−] = 1.0 × 10−14
11 Calculating [H3O+] and [OH–] Hydronium Ions and Hydroxide IonsCalculating [H3O+] and [OH–]If the [H3O+] of a solution is known, the [OH−] can be calculated using Kw.[HCl] = 2.0 × 10−4 M[H3O+] = 2.0 × 10−4 MKw = [H3O+][OH−] = 1.0 × 10−14
12 Determine the hydronium and hydroxide ion concentration in a solution that has 1.0 X M Ca(OH)2 .Ca(OH)2 --> Ca OH-1 mol mol mol1.0 × 10−2 M NaOH solution has an [OH−] of (2) X 1.0 × 10−4 MThe [OH-] concentration is 2.0 X 10-4 MThe [H3O+] of this solution is calculated using Kw.Kw = [H3O+][OH−] = 1.0 × 10−14[H3O+][2.0 X 10-4 M] = 1.0 × 10−14[H3O+] = 5.0 X M
13 Pause for a Cause Student Practice Pg. 522 Problem #8 Calculate the [H3O+] and [OH-] for each of the following:a M HClb. 1.0 X 10-4 M NaOHc X 10-3 M HNO3d M Ca(OH)2Answers: a. [H3O+] = 3.0 X 10-2 M, [OH−] = 3.3 × 10−13 M; b. [H3O+] = 1.0 X M, [OH−] = 1.0 × 10−4 M; c. [H3O+] = 5.0 X 10-3 M, [OH−] = 2.0 × 10−12 M; d. [H3O+] = 5.0 X M, [OH−] = 2.0 × 10−2 M
14 pHpH comes from French words meaning “hydrogen power”. In chemistry, pH is a scale that indicates the concentration of hydronium ions [H3O+] in solutions.
18 When is a solution an acid, a base, or a neutral solution? Solutions in which [H3O+] = [OH−] are neutral.Solutions in which the [H3O+] > [OH−] are acidic.[H3O+] > 1.0 × 10−7 MSolutions in which the [OH−] > [H3O+] are basic.[OH−] > 1.0 × 10−7 M
19 Calculating pHThe pH of a solution is defined as the negative of the common logarithm of the hydronium ion concentration, [H3O+].pH = −log [H3O+]example: a neutral solution has a [H3O+] = 1×10−7The logarithm of 1×10−7 is −7.0.pH = −log [H3O+] = −log(1 × 10−7) = −(−7.0) = 7.0
20 Calculating pH from Hydronium [H3O+] Ions What is the pH of 1.0 X 10-3 M HCl?pH = −log [H3O+] = −log(1.0 × 10−3) = −(−3.0) = 3.0What is the pH of a 1.0 X 10-2 M NaOH solution?pH = −log [H3O+] = −log(1.0 × 10−12) = −(−12) = 12What is the pH of 3.4 X 10-5 M HNO3?pH = −log [H3O+] = −log(3.4 × 10−5) = −(−4.47) = 4.47
21 Pause for a Cause Student Practice Pg. 506 Practice Problems 1-4 What is the pH of a solution if the [H3O+] is 6.7 X 10-4?What is the pH of a solution with a hydronium ion concentration of 2.5 X 10-2 M?Determine the pH of a 2.5 X 10-6 M HNO3 solution.Determine the pH of a 2.0 X 10-2 M Sr(OH)2 solution.Answers: 1) pH = ) pH = ) pH = ) pH = 12.60
22 Determining Hydronium Ions from pH Determine the hydronium ion concentration of an aqueous solution that has a pH of 4.0.[H3O+] = antilog –pH[H3O+] = antilog – 4.0[H3O+] = 1.0 X 10-4
23 The pH of a solution is measured and determined to be 7.52 a. What is the hydronium ion concentration?b. What is the hydroxide ion concentration?c. Is the solution acidic or basic?b. Kw = [H3O+][OH−] = 1.0 × 10−14[3.0 X 10-8][OH-] = 1.0 × 10−14[OH-] = 3.3 X 10-7 Mc. slightly basica. [H3O+] = antilog –pH[H3O+] = antilog – 7.52[H3O+] = 3.0 X 10-8
24 Pause for a Cause Practice Problems Pg. 508 # 1-4 The pH of a solution is determined to be 5.0. What is the hydronium ion concentration of this solution?The pH of a solution is determined to be What is the hydronium ion concentration of this solution?The pH of an aqueous solution is measured as Calculate the [H3O+] and [OH-] concentration.The pH of an aqueous solution is Determine the [H3O+].[H3O+] = 1.0 X 10-5[H3O+] = 1.0 X 10-12[H3O+] = 3.2 X 10-2[ OH-] = 3.2 X 10-12[H3O+] = 2.1 X 10-4
26 The pH of a Substance Can be Found Using Indicators, pH Paper, or pH Meters. Determines the pH of a solution by measuring the voltage between the two electrodes that a placed in the solution.Acid-base indicatorsCompounds whose colors are sensitive to pH.Transition intervalThe pH range over which an indicator changes color.
27 Measuring pH with Wide-Range Paper/ Narrow Range Paper
28 pH Indicators and Their Ranges Problem: An unknown solution is colorless when tested with phenolphthalein, but causes the indicator phenol red to turn red. Use this information to determine the possible pH of this solution.
29 Steps in Determining the Molarity of a Solution. 1. Start with the balanced equation for the neutralization reaction, and determine the chemically equivalent amounts of the acid and base.2. Determine the moles of acid (or base) from the known solution used during the titration.3. Determine the moles of solute of the unknown solution used during the titration.4. Determine the molarity of the unknown solution.
31 Let’s Work this Sample Problem on the Board! In a titration, 27.4 mL of M Ba(OH)2 is added to a 20.0 mL sample of HCl solution of unknown concentration until the equivalence point is reached. What is the molarity of the acid solution?Answer: 4.22 X 10-2 M HCl
32 Let’s Work Another Sample Problem on the Board! A 15.5 mL sample of M KOH solution required21.2 mL of aqueous acetic acid solution in a titration experiment. Calculate the molarity of the acetic acid solution.Answer: M HC2H3O2
33 One Last Sample Problem on the Board! By titration, 17.6 mL of aqueous H2SO4 neutralized 27.4 mL of M LiOH solution. What is the molarity of the aqueous acid solution?Answer: M H2SO4
34 Pause for a Cause Student Practice Pg. 524 # 26, 26, 36 25. Suppose that 15.0 mL of 2.50 X 10-2 M aqueous H2SO4 is required to neutralize 10.0 mL of an aqueous solution of KOH. What is the molarity of the KOH solution?26. In a titration experiment, a 12.5 mL sample of 1.75 M Ba(OH)2 just neutralized 14.5 mL of HNO3 solution. Calculate the molarity of the HNO3 solution.36. Find the molarity of a Ca(OH)2 solution given that 428 mL of the solution is neutralized in a titration by 115 mL of 6.7 X 10-3 M HNO3Answers: X 10-2 M KOH; X 10-2 M HNO3;X 10-4 M Ca(OH)2
35 Challenge Problem Pg. 902 # 359A chemist wants to produce grams of barium sulfate by reacting a M BaCl2 solution with excess H2SO4, as shown in the reaction below. What volume of BaCl2 solution should be used?BaCl2 + H2SO4 BaSO HCl
43 Test Yourself 1. Distilled water contains A. H2O. B. H3O+. C. OH−. D. All of the above
44 Test Yourself 2. What is the pH of a 0.0010 M HNO3? A. 1.0 B. 3.0 C. 4.0D. 5.0
45 Test Yourself3. Which of the following solutions would have a pH value greater than 7?A. [OH−] = 2.4 × 10−2 MB. [H3O+] = 1.53 × 10−2 MC M HClD. [OH−] = 4.4 × 10−9 M
46 Test Yourself 4. If the pH of a solution of the strong base NaOH is known, which property of the solution can becalculated?A. molar concentrationB. [OH−]C. [H3O+]D. All of the above
47 Test Yourself 5. A neutral aqueous solution A. has a 7.0 M H3O+ concentration.B. contains neither hydronium ions norhydroxide ions.C. has an equal number of hydronium ionsand hydroxide ions.D. None of the above
48 Test Yourself6. Identify the salt that forms when a solution of H2SO4 is titrated with a solution of Ca(OH)2.A. calcium sulfateB. calcium hydroxideC. calcium oxideD. calcium phosphate
49 Test Yourself 7. The pH of a solution is 6.32. What is the pOH? B. 4.8 × 10−7C. 7.68D. 2.1 × 10−8
50 Test Yourself 8. The Kw value for water can be affected by: A. dissolving a salt in the solution.B. changes in temperature.C. changes in the hydroxide ionconcentration.D. the presence of a strong acid
51 Test Yourself9. Which of the pH levels listed below is the most acidic?A. pH = 1B. pH = 5C. pH = 9D. pH = 13
52 The End!The End!The End!The End!The End!The End!The End!