Academic Chemistry Newport High School Mrs. Teates

1. Ch. 14 & 15 - Acids & Bases Academic ChemistryNewport High SchoolMrs. Teates

2. Lesson 1 - Properties of Acids and Bases • Essential Questions: • What are the properties of acids and bases?

3. Properties ACIDS BASES • bitter taste • sour taste • turn litmus red • turn litmus blue • react with metals to form H2 gas • slippery feel • ammonia, lye, antacid, baking soda • pH above 7 • vinegar, milk, soda, apples, citrus fruits • pH below 7 ChemASAP

4. Acids Affect Indicators Blue litmus paper turns red in contact with an acid.

5. Bases Affect Indicators Red litmus paper turns blue in contact with a base. Phenolphthalein turns purple in a base.

6. - + Strength • Strong Acid/Base • 100% ionized in water • strong electrolyte HCl HNO3 H2SO4 HBr HI HClO4 NaOH KOH Ca(OH)2 Ba(OH)2

7. - + Strength • Weak Acid/Base • does not ionize completely • weak electrolyte HF CH3COOH H3PO4 H2CO3 HCN NH3

8. Sulfuric Acid – H2SO4 • Highest volume production of any chemical in the U.S. • 37 million metric tons used annually • Used in the production of paper • Used in production of fertilizers • Used in petroleum refining • Used in metallurgy

9. Nitric Acid – HNO3 • Used in the production of fertilizers • Used in the production of explosives, rubber, plastics, dyes, and pharmaceuticals. • Nitric acid is a volatile acid – its reactive components evaporate easily • Stains proteins (including skin!) • Has a suffocating odor, stains skin, and can cause serious burns.

10. Hydrochloric Acid - HCl • Used in the “pickling” of steel • Used to purify magnesium from sea water • Part of gastric juice, it aids in the digestion of proteins • Sold commercially as “Muriatic acid” • Used in industry as a cleaning agent, food processing, activation of oil wells, and production of other chemicals.

11. Phosphoric Acid – H3PO4 • A flavoring agent in sodas • Used in the manufacture of detergents • Used in the manufacture of fertilizers • Not a common laboratory reagent

12. Acetic Acid – HC2H3O2 • Used in the manufacture of plastics • Used in making pharmaceuticals • Acetic acid is the acid present in household vinegar

13. pH Values of Some Common Materials

14. pH testing • There are several ways to test pH • Blue litmus paper (red = acid) • Red litmus paper (blue = basic) • pH paper (multi-colored) • pH meter (7 is neutral, <7 acid, >7 base) • Universal indicator (multi-colored) • Indicators like phenolphthalein • Natural indicators like red cabbage, radishes

15. Indicators of pH • Substances that indicate whether a solution is acidic or basic.

16. pH indicators • Indicators are dyes that can be added that will change color in the presence of an acid or base. • Some indicators only work in a specific range of pH • Once the drops are added, the sample is ruined • Some dyes are natural, like radish skin or red cabbage

17. pH indicators • Universal Indicator – typically a mixtures of many different indicators that changes colors based on the acidity of the solution • Very acidic (pH 0 – 2) – red • Acidic (pH 2 – 7) - orange/yellow • Neutral (pH 7 ) – green • Basic (pH 7 – 12) – blue • Very basic (pH 12 – 14) - purple • Example: Approximately what pH would yellow green be? Approximately what pH would dark green be?

18. Paper testing • Paper tests like litmus paper and pH paper • Put a stirring rod into the solution and stir. • Take the stirring rod out, and place a drop of the solution from the end of the stirring rod onto a piece of the paper • Read and record the color change. Note what the color indicates. • You should only use a small portion of the paper. You can use one piece of paper for several tests.

19. pH paper

20. Maintaining Blood pH Carbon dioxide is exhaled Acid entering the blood stream HCO31- + H+ H2CO3 H2O + CO2 Bicarbonate ion circulates in the blood stream where it is in equilibrium with H+ and OH-. In the lungs, bicarbonate ions combine with a hydrogen ion and lose a water molecule to form carbon dioxide, which is exhaled. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 291

21. Alkalosis If our breathing becomes too fast (hyperventilation)… Carbon dioxide is removed from the blood too quickly. This accelerates the rate of degradation of carbonic acid into carbon dioxide and water. The lower level of carbonic acid encourages the combination of hydrogen ions and bicarbonate ions to make more carbonic acid. The final result is a fall in blood H1+ levels that raises blood pH which can result in over-excitability or death. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 291

22. Acidosis If breathing becomes too slow (hypoventilation)… …free up acid, pH of blood drops, with associated health risks such as depression of the central nervous system or death. The normal pH of blood is between 7.2 – 7.4. This pH is maintained by the bicarbonate ion and other buffers. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 291

23. Binary Acids Is an acid that contains only two different elements. Rules: The name of a binary acid begins with the prefix hydro- The root of the name of the second element follow this prefix. The name then ends with the sufix –ic. Examples HF – hydrofluoric acid HCl – hydrochloric acid HBr – hydrobromic acid Oxyacids and Oxyanions Is an acid that is a compound of hydrogen, oxygen, and a third element, usually a nonmetal. Rules: The names of oxyacids follow a pattern, and the names of their anions are based on the names of the acids. Examples: HClO – hypochlorous acid HClO2 – chlorous acid HClO3 – chloric acid HClO4 – perchloric acid Acid Nomenclature

24. Acid Nomenclature Flowchart

25. Lesson 2 - Acid-Base Theories • Essential Questions: • What are the different acid-base theories? • How are Arrhenius acids and bases, Bronsted-Lowry acids and bases, and Lewis acids and bases similar and different?

26. Acid Base Theories • Arrhenius Acids and Bases • Bronsted-Lowry Acids and Bases • Lewis Acids and Bases

27. Arrhenius Acids and Bases • Developed by Svante Arrhenius • Arrhenius acid – chemical compound that increases the concentration of H+ ions in an aqueous solution. • Arrhenius base – substance that increases the concentration of OH- ions in an aqueous solution

28. H H – + O O Cl Cl H H H H Arrhenius Acids • In aqueous solution… • Acidsform hydronium ions (H3O+) HCl+ H2O  H3O+ + Cl– acid

29. H H – + N O O N H H H H H H H H Arrhenius Base • In aqueous solution… • Bases form hydroxide ions (OH-) NH3+ H2O  NH4+ + OH- base

30. conjugate base conjugate acid Brønsted-Lowry • Acidsare proton (H+) donors. • Bases are proton (H+) acceptors. HCl + H2O  Cl– + H3O+ acid base

31. Conjugate Acids and Bases • Conjugate Acid – species that is formed when a Bronsted-Lowry base gains a proton • Conjugate Base – species that is formed when a Bronsted-Lowry acid gives up a proton. • Conjugate acid-base pair - two substances related to each other by the donating and accepting of a single proton. Acid + Base → conjugate acid + conjugate base •  HCl (aq) + H2O (l) → H3O+ (aq) + Cl- (aq)

32. Example of Bronsted-Lowry H2O + HNO3 H3O+ + NO3– B A CA CB

33. Example of Bronsted-Lowry NH3 + H2O  NH4+ + OH- B A CA CB • Amphoteric - can be an acid or a base.

34. Brønsted-Lowry Acids and Bases Acid = any substance that donates a proton. Base = any substance that accepts a proton. 1- 1+ d+ d- + Cl- H2O H3O+ HCl chloride ion (base) hydronium ion (acid)

35. 1- 1+ + OH- NH4+ hydroxide ion ammonium ion Brønsted-Lowry Acids and Bases d- d+ H2O NH3 (acid) (base)

36. 1- 1+ + OH- NH4+ hydroxide ion ammonium ion Brønsted-Lowry Acids and Bases d- d+ H2O NH3 (acid) (base)

37. Brønsted-Lowry Acids and Bases 1- 1+ d- d+ + OH- H2O NH4+ NH3 hydroxide ion (acid) ammonium ion (base)

38. Brønsted-Lowry Acids and Bases 1- 1+ d- d+ + OH- H2O NH4+ NH3 hydroxide ion (acid) ammonium ion (base)

39. Monoprotic and Polyprotic Acids • Monoprotic acid – acid that can donate only one proton. • Examples: HCl, HF, HNO3 • Polyprotic acid – acid that can donate more than one proton. • Examples: H2SO4, H3PO4 • Turn to page 482 for practice writing equations of Bronsted-Lowry acids and bases.

40. Lewis Acids and Bases • Acidsare electron pair acceptors. • Bases are electron pair donors. Lewis base Lewis acid

41. Lewis Acids and Bases • Lewis acid-base reaction is the formation of one or more covalent bonds between an electron-pair donor and an electron-pair acceptor. • Using electron-dot diagrams, we will practice Lewis acid reactions.

42. Lewis Acid-Base Interactions in Biology • The heme group in hemoglobin can interact with O2 and CO. • The Fe ion in hemoglobin is a Lewis acid • O2 and CO can act as Lewis bases Heme group

43. Definitions Lewis The Arrhenius model of acids and bases was broadened by the Brønsted-Lowry model. The Lewis acid-base model is the most general in scope. The Lewis definition of an acid includes any substance that is an electron pair acceptor; a Lewis base is any substance that can act as an electron pair donor. Brønsted-Lowry Arrhenius

44. Acid and Base Theory Review Interactive Visual Summary

45. Review of Acid-Base Theories • Page 482 Section Review • Page 491 Section 2 Review • Homework worksheet

46. Lesson 3 - Acid-Base Reactions • Essential Questions: • How are conjugate acids and bases different from regular acids and bases? • What are neutralization reactions? • Why does acid rain occur and what is the result of it?

47. Conjugate Acids and Bases • Conjugate Acid – species that is formed when a Bronsted-Lowry base gains a proton • Conjugate Base – species that is formed when a Bronsted-Lowry acid gives up a proton. • Conjugate acid-base pair - two substances related to each other by the donating and accepting of a single proton. Acid + Base → conjugate acid + conjugate base •  HCl (aq) + H2O (l) → H3O+ (aq) + Cl- (aq)

48. F - H2PO4- H2O HF H3PO4 H3O+ Conjugate Bases • Give the conjugate base for each of the following:

49. Br - HSO4- CO32- HBr H2SO4 HCO3- Conjugate Acids • Give the conjugate acid for each of the following:

50. Amphoteric Compounds • Can act as either acid or base. • Examples: • Water • H2O + NH3 → NH4+ + OH− acid base acid base • H2SO4 + H2O → H3O+ + OH− acid base acid base