1. Chapter 9 “Acids and Bases”
Chemistry 140
Chapter 9
“Acids and Bases”

2. CHAPTER OUTLINE 9.1 The Arrhenius Theory 9.2 The Brønsted Theory
9.3 Naming Acids
9.4 The Self‐Ionization of Water
9.5 The pH Concept
9.6 Properties of Acids
9.7 Properties of Bases
9.8 Salts
9.9 The Strengths of Acids and Bases
9.10 Analyzing Acids and Bases
9.11 Titration Calculations
9.12 Hydrolysis Reactions of Salts
9.13 Buffers

3. LEARNING OBJECTIVES/ASSESSMENT
When you have completed your study of this chapter, you should be able to:
1. Write reaction equations that illustrate Arrhenius acid‐base behavior. (Section 9.1; Exercise 9.2)
2. Write reaction equations that illustrate Brønsted acid‐base behavior, and identify Brønsted acids and bases from written reaction equations. (Section 9.2; Exercises 9.6 and 9.10)
3. Name common acids. (Section 9.3; Exercise 9.22)
4. Do calculations using the concept of the self‐ionization of water. (Section 9.4; Exercises 9.28 a & b, and 9.30 a & b)
5. Do calculations using the pH concept. (Section 9.5; Exercises 9.36 and 9.40)
6. Write reaction equations that illustrate the characteristic reactions of acids. (Section 9.6; Exercise 9.50)
7. Write reaction equations that represent neutralization reactions between acids and bases. (Section
9.7; Exercise 9.60)
8. Write reaction equations that illustrate various ways to prepare salts, and do calculations using the concept of an equivalent of salt. (Section 9.8; Exercises 9.68 and 9.74)
9. Demonstrate an understanding of the words weak and strong as applied to acids and bases. (Section 9.9; Exercise 9.86)
10. Demonstrate an understanding of the titration technique used to analyze acids and bases. (Section 9.10; Exercise 9.92)
11. Do calculations related to the analysis of acids and bases by titration. (Section 9.11; Exercises 9.98 and a)
12. Explain the concept of salt hydrolysis, and write equations to illustrate the concept. (Section 9.12; Exercise 9.108)
13. Explain how buffers work, and write equations to illustrate their action. (Section 9.13; Exercise 9.116)

4. Acids and Bases
Acids, bases, and salts are electrolytes, substances whose water solutions conduct electricity.
They are uniquely related in that acids react with bases to produce salts and water.
The word salt is a derivative of the Latin word sal which means vital compound.
Roman soldiers were paid with salt, sal-ary. Salt has long been used to flavor and preserve food and as medicine.

5. The Nature of Acids
Acids are present in many foods, especially fruit. All foods which taste sour have some type of acid in them. Some organic acids include;
ACID FOOD
citric acid lemons
malic acid apples
lactic acid milk
butyric acid rancid butter
acetic acid vinegar

6. Industrial Acids 1. sulfuric acid a. formula - H2SO4 b. dense c. oily
d. high boiling point
e. concentrated - 95%
f. diluted - 1 part acid, 6 parts water
g. uses - car batteries, refining petroleum

7. Industrial Acids (continued)
2. nitric acid
a. formula - HNO3
b. unstable (volatile) in pure form
c. concentrated - 70%
d. diluted - 1 part acid, 5 parts water
e. turns yellow in light
f. uses - fertilizers, explosives

8. Industrial Acids (continued)
3. hydrochloric acid
a. formula - HCl
b. gaseous HCl, extremely soluble in water
c. concentrated - 36%
d. diluted - 1 part acid, 4 parts water
e. uses - steel manufacturing, stomach acid

9. Aqueous Acids
Acids do not display characteristic properties unless they are in water solution. The definition of an electrolyte indicates the necessity of the substance being in a water solution. NEVER ADD WATER TO AN ACID!! Remember this phrase, "do what you oughta, pour the acid in the watta!" The following equations demonstrate ion formation as acids are added to water.
1. Ionization of H2SO4

10. Properties of Acids 1. Acids donate protons in the presence of bases.
HCl monoprotic
H2SO4 diprotic
H+ Cl- + Na+OH- ® Na+Cl- + H+OH-
2. Acids contain ionizable hydrogen covalently bonded to a nonmetallic element or polyatomic species.
nonmetal HCl
polyatomic species...H3PO4

11. Properties of Acids (continued)
3. Acids taste sour. NEVER USE THE TASTE TEST!!!
4. Acids affect indicators.
litmus turns red
phenolphthalein remains clear
methyl orange turns red
5. Acids neutralize hydroxides.
HCl + NaOH ® NaCl + H2O

12. Properties of Acids (continued)
6. Acids react with many metals.
Zn(s) + H2SO4(aq) ® ZnSO4(aq) + H2(g)
7. Acids react with oxides of metals.
CuO + H2SO4 ® CuSO4 + H2O
8. Acids react with carbonates.
CaCO3 + 2HCl ® CaCl2 + H2O + CO2

13. Naming Aqueous Acids HCl ___________________________
1. Binary Acids
a. prefix “hydro”
b. root word
c. suffix "ic"
Examples:
FORMULA NAME
HCl ___________________________
HBr ___________________________
H2S ___________________________
H2Se ___________________________
HI ___________________________

14. Oxyacids
a. prefix
i. “hypo” for ions having one less oxygen than the “ite” ion
ii. no prefix for the “ite” ion
iii. no prefix for the “ate” ion
iv. “per” for ions having one more oxygen than the “ate” ion
b. root name
c. suffix
i. “ous” for the “ite” ion
ii. “ic” for the “ate” ion

15. Oxyacids Containing Halogens
Traditionally, an "X" is used to denote the halogens. The following generalization applies.
HXO4 per - root name - ic
HXO3 root name - ic
HXO2 root name - ous
HXO hypo - root name - ous

16. Examples FORMULA NAME H2SO4 ____________________________
HNO3 ____________________________
HClO3 ____________________________
HClO2 ____________________________
HClO ____________________________
HClO4 ____________________________

17. Acid Anhydrides
Acid anhydrides are oxides which react with water to form acids. To determine an acid anhydride, simply subtract water from the acid in question. Anhydride means without water.
Examples:
ACID ACID ANHYDRIDE
H2SO4 ________________
H3PO4 ________________
H2CO3 ________________

18. Name the following acids and find the acid anhydride where applicable.
FORMULA NAME ANHYDRIDE
H2Te _______________
HNO3 _______________
H3PO4 _______________ __________
H2SeO3 _______________ __________
H3PO3 _______________ __________
H2CO2 _______________ __________
HC2H3O2 ______________

19. Bases
Bases are often referred to as hydroxides. The hydroxide ion, OH-, is responsible for most basic or alkaline properties. The basicity of a substance is also referred to as the alkalinity.
Name some common household bases.
1. lye soap
2. lime antacids
3. laxatives eggs
base - a proton acceptor

20. Properties of Hydroxides
1. Hydroxides of active metals supply hydroxide ions, OH-.
Na+OH- ® Na+(aq) + OH-(aq)
2. Soluble hydroxides have a bitter taste. NEVER USE THE TASTE TEST!!
3. Solutions of hydroxides feel slippery.
4. Soluble hydroxides affect indicators.
red litmus paper turns blue
phenolphthalein turns red
methyl orange turns yellow

21. Properties of Hydroxides (continued)
5. Hydroxides neutralize acids.
NaOH + HCl ® NaCl + H2O
6. Hydroxides react with oxides of nonmetals.
CO2 + 2NaOH ® Na2CO3 + H2O
7. Certain hydroxides are amphoteric; i.e., they take on acid properties in the presence of stronger bases and take on basic properties in the presence of strong acids.
Example: Write the formula for aluminum hydroxide which shows acidic properties.

22. Basic Anhydrides
Oxides which react with water to form solutions containing the hydroxide ion are basic anhydrides.
Find the base anhydride of each of the following.
FORMULA ANHYDRIDE
Ca(OH)2 ____________
Mg(OH)2 ____________
Ba(OH)2 ____________
Al(OH)3 ____________

23. Conjugate Acids and Conjugate Bases
A conjugate base is the species which remains after an acid has given up a proton. A conjugate acid is the species formed when a base takes on a proton. Given the following reaction, complete the reaction equation and identify the conjugate base of sulfuric acid. Also identify the remaining conjugate acid, the reacting acid and reacting base.
H2SO4 + H2O ®
Notice: The stronger an acid, the weaker its conjugate base, the stronger a base, the weaker its conjugate acid.

24. 1. hydrochloric acid + water ® 2. sulfurous acid + water ®
Practice: For each of the following, write the ionic equation, identify the acid, base, conjugate acid, and conjugate base.
1. hydrochloric acid + water ®
2. sulfurous acid + water ®
3. phosphoric acid + water ®
4. acetic acid + water ®

25. Salts
A salt is a compound composed of the positive ion of an aqueous base and the negative ion of an aqueous acid.
We usually think of table salt, NaCl, when we hear the word salt. There are actually many kinds of salts.
Our bodies obtain minerals in the form of salts. For example, with your knowledge of the active metal sodium, what would happen if you tried to eat pure sodium metal?
Eating NaCl is much safer!

26. Salt-Producing Reactions
1. Direct union of elements.
2Na + Cl2 ® 2NaCl
2. Reaction of a metal with an acid.
Zn + 2HCl ® ZnCl2 + H2
3. Reaction of metallic oxide with an aqueous acid.
MgO + 2HCl ® MgCl2 + H2O
4. Reaction of a nonmetallic oxide with a base.
CO2 + Ca(OH)2 ® CaCO3 + H2O

27. Salt-Producing Reactions (continued)
5. Acid-base neutralization.
NaOH + HCl ® NaCl + H2O
6. Ionic reaction.
BaCl2 + Na2SO4 ® 2NaCl + BaSO4
7. Reaction of an acid with a carbonate.
2HCl + Na2CO3 ® 2NaCl + H2O + CO2
8. Reaction of a metallic oxide with a nonmetallic oxide.
MgO + CO2 ® MgCO3

28. Naming Salts
Most compounds which we have learned to name are salts. For each of the following, name the compound and indicate "A" for acid, "B" for base, or "S" for salt.
FORMULA NAME TYPE
H2CO3___________________________ _____
Ba(OH)2__________________________ _____
CuSO4___________________________ _____