2. 7/5/2016 1 Ch 15: Acids What are acids? Acid- substance that donates hydrogen ion(H +, aka proton) to form hydronium (H 3 O + ) ions when dissolved in water; tastes sour Indicator- Litmus red- stays pink for acid, turns blue for base Litmus blue- stays blue for base, turns pink for acid pH paper- shows pH using color Strong acids fully ionize in water (ex. HCl) Strong electrolyte- conducts electricity well Weak acids ionize only a little (acetic acid) Weak electrolyte- does not conduct as well See pg 532: Table 1 & 2 for common Strong/Weak Acids/Bases - + - +

3. 7/5/2016 2 Sulfuric Acid: H 2 SO 4 Strong acid The most common industrial chemical in the world. 47 million tons made each year. Used in refineries & auto batteries. Good dehydrator (drying fruit) because it attracts water. Component of acid rain.

4. 7/5/2016 3 Nitric Acid: HNO 3 Strong acid Volatile, unstable when pure. Stabilized in water. Stains proteins yellow. Suffocating odor, stains/burns skin. Used in making explosives, rubber, plastics, dyes & pharmaceuticals. Turns yellow upon standing.

5. 7/5/2016 4 Phosphoric Acid: H 3 PO 4 Weak acid Phosphorous is essential to plants and animals (energy source at cellular level) Used in making fertilizers & animal feed. Diluted, used as flavoring agents (phosphates) and to clean dairy equipment Sour taste, not toxic if dilute. Also used in making of detergents & ceramics.

6. 7/5/2016 5 Hydrochloric Acid: HCl Strong acid Produced in stomach for digestion. Used in “pickling” iron & other metals to remove impurities. Used to recover magnesium from sea water. Dilute is called muriatic acid -- for swimming pools & cleaning masonry.

7. 7/5/2016 6 Acetic Acid: CH 3 COOH Weak acid Concentrated form is called glacial acetic acid. “Glacial” since can form crystals at 17ºC Found in vinegar (4 - 8% acetic acid). Used to make food supplements like lysine (an essential amino acid). Used as a fungicide.

8. 7/5/2016 7 The following picture shows a light bulb connected to a battery with the circuit interrupted by a solution. When dissolved in the water to form a 1.0 molar solution, all of the following substances will complete a circuit allowing the bulb to light except A hydrochloric acid. B sodium nitrate. C sucrose. D ammonium sulfate.

9. 7/5/2016 8 Bases What are bases? Base- contains hydroxide ion or reacts with water to produce hydroxide ion (OH - ) Proton acceptor Many bases contain OH - Ex. KOH  K + + OH - Some reacts with water to produce OH - Ex. NH 3 + H 2 O  NH 4 + + OH -

10. 7/5/2016 9 Some Common Bases NaOHsodium hydroxide KOH potassium hydroxide Ba(OH) 2 ________________________ Mg(OH) 2 ________________________ Al(OH) 3 aluminum hydroxide Barium Hydroxide Magnesium Hydroxide

11. 7/5/2016 10 Names and Formulas for Acids and Bases Acid nomenclature -ide: hydro-- ic acid -ite:-ous acid -ate: -ic acid Bases: cation followed by anion (no change)

12. 7/5/2016 11 Learning Check Give the name of the following A. HBr (aq)1. bromic acid 2. bromous acid 3. hydrobromic acid 3. hydrobromic acid The name of a non-oxyacid begins with the prefix hydro- and ends with -ic acid. In a non-oxyacid, the negative anion end in - ide.

13. 7/5/2016 12 Learning Check Give the name of the following B. H 2 CO 3 1. carbonic acid 2. hydrocarbonic acid 3. carbonous acid 1. carbonic acid The name of an oxyacid is named with the stem of the anion (carbonate) changed to -ic acid (No “hydro”)

14. 7/5/2016 13 Learning Check AB4 Match the formulas with the names: A. ___ HNO 2 1) hydrochloric acid B. ___Ca(OH) 2 2) sulfuric acid C. ___H 2 SO 4 3) sodium hydroxide D. ___HCl4) nitrous acid E. ___NaOH5) calcium hydroxide 4 5 2 1 3

15. 7/5/2016 14 Learning Check Acid, Base Name or Salt CaCl 2 _______________________ KOH_______________________ Ba(OH) 2 ______ _________________ HBr_______________________ H 2 SO 4 ________________________ Salt Calcium Chloride BasePotassium Hydroxide BaseBarium Hydroxide AcidHydrobromic Acid Acid Sulfuric Acid

16. 7/5/2016 15 B. Definitions Arrhenius - In aqueous solution… HCl + H 2 O  H 3 O + + Cl – Acids Acids form hydronium ions (H 3 O + ) H HHHH H Cl OO – + acid

17. 7/5/2016 16 B. Definitions Arrhenius - In aqueous solution… Bases Bases form hydroxide ions (OH - ) NH 3 + H 2 O  NH 4 + + OH - H H H H H H N NO O – + H H H H base

18. 7/5/2016 17 Bronsted-Lowry Acids Acids are hydrogen ion (H + ) (or proton) donors Bases are hydrogen ion (H + ) acceptors HCl + H 2 O H 3 O + + Cl - donor acceptor + - +

19. 7/5/2016 18 NH 3, A Bronsted-Lowry Base When NH 3 reacts with water, most of the reactants remain dissolved as molecules, but a few NH 3 reacts with water to form NH 4 + and hydroxide ion. LD 4:15.17 NH 3 /H 2 O reaction. NH 3 + H 2 O NH 4 + (aq) + OH - (aq) acceptor donor+

20. 7/5/2016 19 Acid-Base Systems

21. 7/5/2016 20 electrolytes  electrolytes turn litmus red sour taste react with metals to form H 2 gas slippery feel turn litmus blue bitter taste, chalky vinegar, milk, soda, apples, citrus fruits ammonia, lye, antacid, baking soda Produces H 3 0 + in water  produces OH - in water

22. 7/5/2016 21 Learning Check AB1 Describe the solution in each of the following as: 1) acid 2) base or 3)neutral. A. ___soda B. ___soap C. ___coffee D. ___ wine E. ___ water F. ___ grapefruit 1 2 1 1 3 1

23. 7/5/2016 22 Learning Check Identify each as characteristic of an A) acid or B) base ____ 1. Sour taste ____ 2. Produces OH - in aqueous solutions ____ 3. Chalky taste ____ 4. Is an electrolyte ____ 5. Produces H + in aqueous solutions A B B Both A

24. 7/5/2016 23 B. Definitions Brønsted-Lowry HCl + H 2 O  Cl – + H 3 O + Acids Acids are proton (H + ) donors. Bases Bases are proton (H + ) acceptors. conjugate acid conjugate base baseacid

25. 7/5/2016 24 Which of the following is an observable property of many acids? A They become slippery when reacting with water. B They react with metals to release hydrogen gas. C They produce salts when mixed with other acids. D They become more acidic when mixed with a base. Potassium hydroxide (KOH) is a strong base because it A easily releases hydroxide ions. B does not dissolve in water. C reacts to form salt crystals in water. D does not conduct an electric current.

26. 7/5/2016 25 Behavior of acids of different strengths in aqueous solution.

27. 7/5/2016 26 Strength Strong acids and bases are strong electrolytes Strength is different from concentration Strong - forms many ions when dissolved Mg(OH) 2 is a strong base - it falls completely apart when dissolved. But, not much dissolves - not concentrated The words concentrated and dilute tell how much of an acid or base is dissolved in solution - refers to the number of moles of acid or base in a given volume The words strong and weak refer to the extent of ionization of an acid or base Is a concentrated weak acid possible? Yes!

28. 7/5/2016 27 Which of the following "molecular" pictures, “A” or “B”, best represents a concentrated solution of the weak acid HA with Ka = 10 -5 ?... “B”, because... There are more molecules of undissociated form. “A” represents a strong acid.

29. 7/5/2016 28 Learning Check SW1 Identify each of the following as a 1) strong acid or base 2) weak acid 3) weak base A. ___ HCl (aq) B. ___ NH 3 (aq) C. ___ NaOH (aq) D. ___ H 2 CO 3 (aq) 1 3 1 2

30. 7/5/2016 29

31. 7/5/2016 30 pH How Acidic Is an Acid? power of hydronium ion (pH): measure of the hydronium ion concentration in a solution 7 greater than 7 is basic less than 7 is acidic neutral greater than 7 is basic Each unit of pH represents 10 Ex. The difference btwn 3 and 5 is 100 times How does hyperventilation ( breathing out too rapidly and deeply) upset the pH of the blood?

32. 7/5/2016 31 Pure Water is Neutral Pure water contains small, but equal amounts of ions: H 3 O + and OH - H 2 O + H 2 O H 3 O + + OH - hydronium hydroxide ion ion 1 x 10 -7 M H3O+H3O+ OH -

33. 7/5/2016 32 Ion Product of Water K w [ ] = Molar concentration K w = [ H 3 O + ] [ OH - ] = [ 1 x 10 -7 ][ 1 x 10 -7 ] = 1 x 10 -14

34. 7/5/2016 33 Do “A” in your head if you can A.The [OH - ] when [H 3 O + ] of 1 x 10 - 4 M 1) 1 x 10 -6 M 2) 1 x 10 -8 M 3) 1 x 10 -10 M 3) 1 x 10 -10 M B.The [H 3 O + ] when [OH - ] of 5 x 10 -9 M 1) 1 x 10 - 6 M 2) 2 x 10 - 6 M 3) 2 x 10 -7 M 2) 2 x 10 - 6 M Steps...

35. 7/5/2016 34 pH and pOH [H + ] x [OH - ] = 1 x 10 -14 pH = -log [H + ] [H + ] = antilog (-pH) …this is 2 nd log not ln = 10 x pH + pOH = 14 pOH = -log [OH - ] [OH - ] = antilog (-pOH) Thus, a solution with a pOH less than 7 is basic; with a pOH greater than 7 it is an acid.

36. 7/5/2016 35 Of four different laboratory solutions, the solution with the highest acidity has a pH of A 11.B 7.C 5.D 3

37. 7/5/2016 36 Learning Check pH4 A. The [H 3 O + ] of tomato juice is 1 x 10 -4 M. What is the pH of the solution? 1) - 42)43)8 B. The [OH - ] of an ammonia solution is 1 x 10 -3 M. What is the pH of the solution? 1) 32)113)-11 * *

38. 7/5/2016 37 Solution pH4 A. pH = - log [ 1 x 10 -4 ] = -(- 4) = 4 B. [H 3 O + ] = 1 x 10 -11 pH = - log [ 1 x 10 - 11 ] = -(- 11) = 11

39. 7/5/2016 38 Learning Check pH5 The pH of a soap is 10. What is the [H 3 O + ] of the soap solution? 1) 1 x 10 -4 M 2) 1 x 10 10 M 3) 1 x 10 -10 M [H 3 O + ] = 1 x 10 -pH M = 1 x 10 -10 M Acidic or Basic?... Basic

40. 7/5/2016 39 Learning Check pH6 A soap solution has a [H 3 O + ] = 2 x 10 -8 M. What is the pH of the solution? 1)8 2) 7.7 3)6 *** Steps...

41. 7/5/2016 40 Solution pH6 A soap solution has a [H 3 O + ] = 2.0 x 10 -8 M. What is the pH of the solution? pH = -log [H 3 O + ] so... B) +/- LOG 2.0 EE +/- 8 = 7.7 Acidic or Basic?... Basic

42. 7/5/2016 41 Learning Check pH7 Identify each solution as 1. acidic 2. basic3. neutral A. _____ HCl with a pH = 1.5 B. _____ Pancreatic fluid [H + ] = 1 x 10 -8 M C. _____ Sprite soft drink pH = 3.0 D. _____ pH = 7.0 E. _____ [OH - ] = 3 x 10 -10 M F. _____ [H + ] = 5 x 10 -12 1 2 1 3 1 2

43. 7/5/2016 42 pH on the Calculator [H 3 O + ] is 4.5 x 10 -6 M pH = +/- LOG 4.5 EXP(or EE) +/- 6 ENTER = 5.35

44. 7/5/2016 43 One More Problem Given pH = 7.52, is it acidic or basic and what is pOH, [H 3 O 1+ ] and [OH 1- ]? The pH tells us it must be which?... Basic since > than 7.00. pOH = ?... 6.48 since pH + pOH = 14.00 [H 3 O 1+ ] = 10 -pH so [H 3 O 1+ ] = ?... 2nd log ± 7.52 = [H 3 O 1+ ] = 3.02 x 10 -8

45. 7/5/2016 44 One More Problem Given [H 3 O 1+ ] = 3.02 x 10 -8 and pOH = 6.48, both just calculated, what is [OH 1- ]? [OH 1- ] = 10 -pOH = ?... 2nd log ± 6.48 = 3.31 x 10 -7 Can also do by K w = [H 3 O 1+ ][OH 1- ] [OH 1- ] = 1.0 x 10 -14 /3.02 x 10 -8 =...? 1 EE ± 14 ÷ 3.02 EE ± 8 = 3.31 x 10 -7

46. 7/5/2016 45 Neutralization Neutralization Reactions Strong acids and strong bases react to form a salt and water HCl + NaOH  _____ + _____ Depends on the strength and amount of acids and bases used Neutralization does not mean pH = 7. When acid and bases with equal amounts of hydrogen ion H + and hydroxide ions OH - are mixed, the resulting solution is neutral. NaCl H 2 O

47. 7/5/2016 46 Ionic Equations for Neutralization HCl + NaOHHOH + NaCl Write strong acids, bases & soluble salts as ions H + + Cl - + Na + + OH - Na + + Cl - + H 2 O Cross out matched ions H + + Cl - + Na + + OH - Na + + Cl - + H 2 O Write a net ionic reaction H + + OH - H 2 O

48. 7/5/2016 47 Equal volumes of 1 molar hydrochloric acid (HCl) and 1 molar sodium hydroxide base (NaOH) are mixed. After mixing, the solution will be A strongly acidic. B weakly acidic. C nearly neutral. D weakly basic.

49. 7/5/2016 48 Discuss with your neighbor… Many acids and bases are used daily in our homes. Based on what you know about the properties of acids and bases, answer the following items. Some green apples are particularly sour. Is this likely to be due to an excess of acid or base? Baking soda reacts with vinegar. Is baking soda an acid or base? Given that one approach to an upset stomach is to take an antacid, are the chemicals secreted into the stomach for digestion likely to be acids or bases? Drain cleaners that contain lye react with fatty acids in clogs. Given that, are drain cleaners that contain lye acids or bases? Many common window cleansers contain ammonia, a base. Given that, is most dirt on window slightly acidic or slightly basic?