1. Ch # 6
Acids, Bases and Salts

2. ACIDS
An acid “is a hydrogen-containing substance that produces hydrogen ions” in water. (Hydronium ion: H3O+)
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
FeCl3 A metal ion that is acidic
CO32- An anion that is basic
NH4+ A cation that is acidic

12. Salts
A salt is an ionic compound containing a metal cation and a nonmetal anion
Produced in a neutralization reaction: HCl + NaOH  H2O + NaCl

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

14. Strong acids & bases – strong electrolyte
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:
Kw = [H3O+] [OH-] = 1.00 x 10-14
If [H3O+] = 7.50 x 10-5 M What is the [OH-] in this solution?

21. pH = -log [H3O+]
= -log [H+]

25. 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:
[H3O+] = 1 X 10-3
[H3O+] = 1 X 10-9
[OH-] = 1 X 10-4
[H3O+] = 3.9 X 10-5
[H3O+] = 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 What is the molar hydronium ion concentration for this solution?
[H3O+] = 10-pH

30. 6.7 Preparation of Acids H2(g) + Cl2(g)  2HCl(g)
2NaCl + H2SO4  2HCl(g) + Na2SO4
SO2(g) + H2O  H2SO3

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 NaHCO3 and Na2CO3 (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 Ca5OH(PO4)3
Reactions:
NaHCO3 + NaOH  Na2CO3 + H2O

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
CaSO4▪2H2O calcium sulfate dihydrate
(gypsum-dry wall, plaster of paris, Dri-rite)
CuSO4▪5H2O copper(II) sulfate pentahydrate