Chemistry Slide 1 of 50

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1 Chemistry of 50

2 19.2 Hydrogen Ions and Acidity To test a diagnosis of diabetic coma, a doctor orders several tests, including the acidity of the patient s blood. Results from this test will be expressed in units of ph. You will learn how the ph scale is used to indicate the acidity of a solution and why the ph scale is used. 2 of 50

3 19.2 Hydrogen Ions and Acidity > Hydrogen Ions from Water Hydrogen Ions from Water The reaction in which water molecules produce ions is called the self-ionization of water. 3 of 50

4 19.2 Hydrogen Ions and Acidity > Hydrogen Ions from Water In the self-ionization of water, a proton (hydrogen ion) transfers from one water molecule to another water molecule. 4 of 50

5 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water Ion Product Constant for Water How are [H + ] and [OH - ] related in an aqueous solution? 5 of 50

6 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water For aqueous solutions, the product of the hydrogen-ion concentration and the hydroxide-ion concentration equals Any aqueous solution in which [H + ] and [OH - ] are equal is described as a neutral solution. 6 of 50

7 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water The product of the concentrations of the hydrogen ions and hydroxide ions in water is called the ion-product constant for water (K w ). 7 of 50

8 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water An acidic solution is one in which [H + ] is greater than [OH - ]. 8 of 50

9 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water Unrefined hydrochloric acid, commonly called muriatic acid, is used to clean stone buildings and swimming pools. 9 of 50

10 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water A basic solution is one in which [H + ] is less than [OH ]. Basic solutions are also known as alkaline solutions. 10 of 50

11 19.2 Hydrogen Ions and Acidity > Ion Product Constant for Water Sodium hydroxide, or lye, is commonly used as a drain cleaner. 11 of 50

12 SAMPLE PROBLEM of 50

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16 Practice Problems for Sample Problem 19.1 Problem Solving Solve Problem 10 with the help of an interactive guided tutorial. 16 of 50

17 19.2 Hydrogen Ions and Acidity > The ph Concept The ph Concept How is the hydrogen-ion concentration used to classify a solution as neutral, acidic, or basic? 17 of 50

18 19.2 Hydrogen Ions and Acidity > The ph Concept The ph of a solution is the negative logarithm of the hydrogen-ion concentration. 18 of 50

19 19.2 Hydrogen Ions and Acidity > The ph Concept Calculating ph 19 of 50

20 19.2 Hydrogen Ions and Acidity > The ph Concept A solution in which [H + ] is greater than M has a ph less than 7.0 and is acidic. The ph of pure water or a neutral aqueous solution is 7.0. A solution with a ph greater than 7 is basic and has a [H + ] of less than M. 20 of 50

21 19.2 Hydrogen Ions and Acidity The ph Concept > 21 of 50

22 19.2 Hydrogen Ions and Acidity > The ph Concept 22 of 50

23 19.2 Hydrogen Ions and Acidity > The ph Concept Calculating poh 23 of 50

24 19.2 Hydrogen Ions and Acidity > The ph Concept ph and Significant Figures 24 of 50

25 SAMPLE PROBLEM of 50

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29 Practice Problems for Sample Problem 19.2 Problem Solving Solve Problem 12 with the help of an interactive guided tutorial. 29 of 50

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34 Practice Problems for Sample Problem 19.3 Problem Solving Solve Problem 14 with the help of an interactive guided tutorial. 34 of 50

35 19.2 Hydrogen Ions and Acidity > Measuring ph Measuring ph What is the most important characteristic of an acid-base indicator? 35 of 50

36 19.2 Hydrogen Ions and Acidity > Measuring ph An indicator is a valuable tool for measuring ph because its acid form and base form have different colors in solution. 36 of 50

37 19.2 Hydrogen Ions and Acidity > Measuring ph Phenolphthalein changes from colorless to pink at ph of 50

38 SAMPLE PROBLEM of 50

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42 Practice Problems for Sample Problem 19.4 Problem Solving Solve Problem 15 with the help of an interactive guided tutorial. 42 of 50

43 19.2 Hydrogen Ions and Acidity > Measuring ph Acid-Base Indicators 43 of 50

44 19.2 Hydrogen Ions and Acidity > Measuring ph 44 of 50

45 19.2 Hydrogen Ions and Acidity > Measuring ph Universal Indicators 45 of 50

46 19.2 Hydrogen Ions and Acidity > Measuring ph ph Meters 46 of 50

47 19.2 Section Quiz. Assess students understanding of the concepts in Section Continue to: Section Quiz -or- Launch: 47 of 50

48 19.2 Section Quiz. 1. If the [OH - ] in a solution is M, what is the [H + ] of this solution? a M b M c. 2.12M d M 48 of 50

49 19.2 Section Quiz. 2. The [OH - ] for four solutions is given below. Which one of the solution is basic? a. 1.0 x 10-6 M b. 1.0 x 10-8 M c. 1.0 x 10-7 M d. 1.0 x M 49 of 50

50 19.2 Section Quiz. 3. What is the ph of a solution with a hydrogenion concentration of 8.5 x 10-2 M? a b c d of 50

51 END OF SHOW