1. Chapter 7 Acids and Bases John Singer, Jackson Community College Chemistry for Changing Times, Thirteenth Edition Lecture Outlines © 2013 Pearson Education, Inc.

2. 2 Chapter 7 © 2013 Pearson Education, Inc. Acids and Bases: Experimental Definitions Acids: Taste sour. Turn litmus red. React with active metals to release hydrogen gas. React with bases to form water and a salt.

3. 3 Chapter 7 © 2013 Pearson Education, Inc. Bases: Taste bitter. Turn litmus blue. Feel slippery. React with acids to form water and a salt. Acids and Bases: Experimental Definitions

4. 4 Chapter 7 © 2013 Pearson Education, Inc. Acids and Bases: Experimental Definitions

5. 5 Chapter 7 © 2013 Pearson Education, Inc. Acids, Bases, and Salts Arrhenius Theory Acid: A molecular substance that ionizes in aqueous solution to form hydrogen ions (H + ).

6. 6 Chapter 7 © 2013 Pearson Education, Inc. Arrhenius Theory Base: A substance that produces hydroxide ions (OH-) in aqueous solution. Acids, Bases, and Salts

7. 7 Chapter 7 © 2013 Pearson Education, Inc. Neutralization: When an acid reacts with a base, the properties of each are neutralized and the products are water and a salt. Acid + Base → Water + Salt Acids, Bases, and Salts

8. 8 Chapter 7 © 2013 Pearson Education, Inc. Limitations of the Arrhenius Theory H + ions do not exist in water solution. Protons react with water to form hydronium ions (H 3 O + ). H + + H 2 O → H 3 O + The Arrhenius theory does not explain the basicity of ammonia and similar compounds. It only applies to reactions in aqueous solution. Acids, Bases, and Salts

9. 9 Chapter 7 © 2013 Pearson Education, Inc. Brønsted-Lowry Theory Acid: Proton donor HCI + H 2 O → H 3 O + + CI - Base: Proton acceptor NH 3 + H 2 O → NH 4 + + OH - Acids, Bases, and Salts

10. 10 Chapter 7 © 2013 Pearson Education, Inc. Brønsted-Lowry Theory Acids, Bases, and Salts

11. 11 Chapter 7 © 2013 Pearson Education, Inc. Salts are ionic compounds composed of cations other than hydrogen and anions other than hydroxide. Acids, Bases, and Salts

12. 12 Chapter 7 © 2013 Pearson Education, Inc. Anhydride means without water. Nonmetal oxides are acidic anhydrides. SO 3 + H 2 O → H 2 SO 4 Acids, Bases, and Salts

13. 13 Chapter 7 © 2013 Pearson Education, Inc. Acidic and Basic Anhydrides Metal oxides are basic anhydrides. Example: Lime (calcium oxide) reacts with water to form slaked lime (calcium hydroxide). CaO + H 2 O → Ca(OH) 2

14. 14 Chapter 7 © 2013 Pearson Education, Inc. Strong acids ionize completely in water solution. HCl(aq) → H + (aq) + Cl - (aq) Weak acids only partially ionize in water solution. HCN(aq) ↔ H + (aq) + CN - (aq) Strong and Weak Acids and Bases

15. 15 Chapter 7 © 2013 Pearson Education, Inc. Strong bases ionize or dissociate completely in water solution. NaOH(aq) → Na + (aq) + OH - (aq) Weak bases only partially ionize in water solution. NH 3 (aq) + H 2 O ↔ NH 4 + (aq) + OH - (aq) Strong and Weak Acids and Bases

16. 16 Chapter 7 © 2013 Pearson Education, Inc. Ammonia accepts a proton from water, forming a basic solution. Strong and Weak Acids and Bases

17. 17 Chapter 7 © 2013 Pearson Education, Inc. Neutralization The reaction of an acid with a base is called neutralization. Water molecules are the result of the reaction between hydrogen ions and hydroxide ions. H + + OH - ↔ H 2 O

18. 18 Chapter 7 © 2013 Pearson Education, Inc. During neutralization, an acid reacts with a base, forming water and a salt. Neutralization

19. 19 Chapter 7 © 2013 Pearson Education, Inc. The amount of acid (or base) in a solution is determined by careful neutralization. Neutralization

20. 20 Chapter 7 © 2013 Pearson Education, Inc. The pH Scale pH is a means of expressing the acidity or basicity of a solution.

21. 21 Chapter 7 © 2013 Pearson Education, Inc. pH means “power” of hydrogen. pH = -log[H + ] The pH Scale

22. 22 Chapter 7 © 2013 Pearson Education, Inc. The pH Scale

23. 23 Chapter 7 © 2013 Pearson Education, Inc. Conjugate acid-base pairs are compounds or ions that differ by one proton (H + ). For example, the chloride ion (Cl - ) is the conjugate base of the acid, hydrochloric acid (HCl). Buffers and Conjugate Acid- Base Pairs

24. 24 Chapter 7 © 2013 Pearson Education, Inc. Buffer solutions contain a weak acid and its conjugate base. Such solutions are capable of maintaining a nearly constant pH when small amounts of acid or base are added. Buffers and Conjugate Acid- Base Pairs

25. 25 Chapter 7 © 2013 Pearson Education, Inc. Acid Rain Nonmetal oxides present in air react with water, forming acidic solutions. Rain with a pH of less than 5.6 is considered to be acid rain. Carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), nitrogen monoxide (NO), and nitrogen dioxide (NO 2 ) are the major nonmetallic oxides responsible for acid rain formation.

26. 26 Chapter 7 © 2013 Pearson Education, Inc. Antacids: A Basic Remedy Hyperacidity is when the stomach secretes too much acid. Antacids are often taken to neutralize excess acid and reduce the symptoms of hyperacidity. Excessive use of antacids can lead to an increase in the pH of blood, a condition known as alkalosis.

27. 27 Chapter 7 © 2013 Pearson Education, Inc. Antacids: A Basic Remedy

28. 28 Chapter 7 © 2013 Pearson Education, Inc. SubstanceFormulaProduct(s) Sodium bicarbonate NaHCO 3 Baking soda Calcium carbonate CaCO 3 Tums® Aluminum hydroxide Al(OH) 3 Amphojel® Magnesium hydroxide Mg(OH) 2 Milk of Magnesia® Antacids: A Basic Remedy

29. 29 Chapter 7 © 2013 Pearson Education, Inc. Acid Reducers Acid Reducers have been displacing antacids as a way to combat hyperacidity.

30. 30 Chapter 7 © 2013 Pearson Education, Inc. Sulfuric acid is the leading chemical substance produced in the U.S. It is used to manufacture fertilizers and industrial chemicals. It is the acid of automotive batteries. Production is 40 billion kg/year. Acids and Bases in Industry and at Home

31. 31 Chapter 7 © 2013 Pearson Education, Inc. Hydrochloric acid has a number of uses. It is used as a rust remover, and it removes lime from mortar and household plumbing fixtures. It can be purchased from hardware stores as muriatic acid. Annual U.S. production is 4 billion kg. Acids and Bases in Industry and at Home

32. 32 Chapter 7 © 2013 Pearson Education, Inc. Lime (CaO) is produced by heating limestone (CaCO 3 ). CaCO 3 + heat → CaO + CO 2 Lime can be slaked by reacting with water to make calcium hydroxide (Ca(OH) 2 ). Slaked lime is used to make mortar and cement and to sweeten soil. Annual U.S. production is 22 billion kg. Acids and Bases in Industry and at Home

33. 33 Chapter 7 © 2013 Pearson Education, Inc. Soil can be “sweetened” by adding slaked lime [Ca(OH) 2 ]. Acids and Bases in Industry and at Home

34. 34 Chapter 7 © 2013 Pearson Education, Inc. Sodium hydroxide, also known as lye, can be purchased for home use as oven cleaner or drain cleaners. It is used commercially to make soap. Annual U.S. production is 9 billion kg. Acids and Bases in Industry and at Home

35. 35 Chapter 7 © 2013 Pearson Education, Inc. Ammonia is produced for use as fertilizer and in household cleaning products. Production is about 11 billion kg/year. Acids and Bases in Industry and at Home

36. 36 Chapter 7 © 2013 Pearson Education, Inc. Concentrated acids and bases are corrosive to tissue and are health hazards. They can denature proteins in living cells. The human body has wonderful mechanisms for maintaining the proper pH of tissue, blood, and body fluids. Acids and Bases in Industry and at Home