1. Ch # 6 Acids, Bases and Salts

2. ACIDS An acid “is a hydrogen-containing substance that produces hydrogen ions” in water. (Hydronium ion: H 3 O + ) An aqueous solution that contains more H + ions than OH - ions is ‘acidic’

4. ACID PROPERTIES Sour taste (think lemons and sour candies) Change the color of litmus from blue to red.

5. Acid Properties (cont.) React with a base to produce water and salt in a double displacement neutralization reaction. React with metals such as zinc and magnesium to produce hydrogen gas in a single replacement reaction.

6. BASES An base is a hydroxide-containing substance that dissociates to produce hydroxide ions in aqueous solution. An aqueous solution that contains more OH - ions than H + ions is ‘basic’

7. BASE PROPERTIES Bitter or caustic taste. A slippery, soapy feeling. The ability to change litmus red to blue. The ability to interact with acids in a neutralization reaction to produce water and salt.

8. Ionization/Dissociation. Ionization: A process in which ions are produced from a molecular compound when dissolved in a solvent. ACIDS Dissociation: A process in which already existing ions in an ionic compound separate when an ionic compound is dissolved in a solvent. BASES

10. Amphoteric substances Glycine Hydrogen carbonate

11. Other kinds of acids and bases FeCl 3 A metal ion that is acidic CO 3 2- An anion that is basic NH 4 + A cation that is acidic

12. A salt is an ionic compound containing a metal cation and a nonmetal anion Produced in a neutralization reaction: HCl + NaOH  H 2 O + NaCl Salts

13. 6.3 Conductance of A, B, S Solutions Strong electrolyte Weak electrolyte Non-electrolyte

14. 6.4 Dissociation of A & B Strong acids & bases – strong electrolyte Weak acids & bases – weak electrolyte

17. 6.5 Buffers A solution that resists major changes in pH when small amounts of acid or base is added to it. 1) A substance to react with and remove added base. 2) A substance to react with and remove added acid. 3) weak acid-salt.

18. 6.6 pH and Acidic / Basic Solutions

20. Self ionization of water: Ion product constant for water: K w = [H 3 O + ] [OH - ] = 1.00 x 10 -14 If [H 3 O + ] = 7.50 x 10 -5 M What is the [OH - ] in this solution?

21. pH = -log [H 3 O + ] = -log [H + ]

25. H3O+H3O+

26. Acidic solution: [H3O+]> [OH-] pH= 0-6 Basic solution: [H3O+]< [OH-] pH =8-14 Neutral solution: [H3O+]= [OH-] pH =7 pH scale: Scale that is used to specify molar hydronium ion concentration in an aqueous solution.

27. Problems Calculate pH for the following and identify as acidic or basic: [H 3 O + ] = 1 X 10 - 3 [H 3 O + ] = 1 X 10 -9 [OH - ] = 1 X 10 -4 [H 3 O + ] = 3.9 X 10 -5 [H 3 O + ] = 7.9 X 10 -11 The number of decimal places of a logarithm is equal to the number of significant figures in the original number.

28. Problem The pH of a solution is 5.70. What is the molar hydronium ion concentration for this solution? [H 3 O + ] = 10 -pH

30. 6.7 Preparation of Acids H 2(g) + Cl 2(g)  2HCl (g) 2NaCl + H 2 SO 4  2HCl (g) + Na 2 SO 4 SO 2(g) + H 2 O  H 2 SO 3

31. 6.8 Preparation of bases: Alkali metal and water to produce hydrogen and a hydroxide salt. Ammonia in water Carbonate in water

32. 6.9 Preparation of Salts The reaction of an acid with a base is called a neutralization reaction. In an aqueous solution the products are a salt and water. Solvay process for making NaHCO 3 and Na 2 CO 3 (p226)

33. Reactions of salts: Reaction with metals: Single replacement reaction according to activity series. Reaction with acids: Double displacement reaction. A new weaker acid, new insoluble salt, gaseous compound is one of the products. Reaction with bases: Insoluble precipitate forms, or weaker base. Reaction of salts with each other: Double displacement reaction. Insoluble salt is formed.

34. 6.10 Acidic and Basic Salts Ions that contain H + Bases: See Page 213 Hydroxyapatite Ca 5 OH(PO 4 ) 3 Reactions: NaHCO 3 + NaOH  Na 2 CO 3 + H 2 O

35. 6.11 Water of Hydration Water binds to some salts: These are hydrates. They are used as desiccants (drying agents). A desiccant is a hygroscopic substance that induces or sustains a state of dryness (desiccation) in its vicinity. Anhydrous (without water of hydration)

36. Examples and names CaSO 4 ▪2H 2 O calcium sulfate dihydrate (gypsum-dry wall, plaster of paris, Dri-rite) CuSO 4 ▪5H 2 O copper(II) sulfate pentahydrate