Acids and Bases

1
Chapter 15

• Acids and Bases

2
Arrhenius Acid-Base Theory

• Arrhenius, Svante August
• (1859-1927), Swedish chemist
• 1903 Nobel Prize in chemistry
• acid - proton donor
• base - hydroxide ion donor

3
Bronsted-Lowry Acid-Base Theory

• acid - proton donor
• base - proton acceptor
• strong vs. weak acids and bases
• strong - completely ionized
• weak - partially ionized

4
Acid-Base Reactions

• hydronium ion
• hydrated proton, H3O
• used interchangeably for H
• indicators
• natural or synthetic substance that changes color
  in response to the nature of its chemical
  environment.

5
Indicators

• Indicators are used to provide information about
  the degree of acidity of a substance (pH) or the
  state of some chemical reaction within a solution
  being tested or analyzed.

6
Indicators

• One of the oldest indicators is litmus, a
  vegetable dye that turns red in acid solutions
  and blue in basic ones. Other indicators include
  alizarin, methyl red, and phenolphthalein, each
  one being useful for a particular range of
  acidity or a certain type of chemical reaction.

7
Indicators
8
Neutralization Reactions

• acid base ---gt salt water
• HCl NaOH ---gt NaCl H2O

9
Sulfur Acid

• SO3 H2O -----gt H2SO4

10
Phosphoric Acid

• P4O10(s) 6H2O(l) ---gt 4H3PO4(aq)

11
Strong vs. Weak Acids and Bases

• strong acid
• completely ionized
• weak acid
• partially ionized

12

• Which of the following "molecular" pictures best
  represents a concentrated solution of the weak
  acid HA with Ka 10-5?
• A, B

13
Autoionization of Water

• H2O H2O ltgt H3O OH-
• H3OOH-
• K -----------------
• H2O2
• Kw K H2O2 H3OOH- 1.0 x 10-14

14
Autoionization of Water

• Kw K H2O2 H3OOH- 1.0 x 10-14
• H3OH3O 1.0 x 10-14
• H3O2 1.0 x 10-14
• H3O 1.0 x 10-7
• -log(H3O) -log(1.0 x 10-7)
• pH -log(H3O) 7.00

15
pH Scale

• _at_ -2 -----gt _at_ 16
• pH - log H3O

16

• A solution with pH5 is 100 times more acidic
  than a solution with a pH ?
• 7, 3, 0.05

17
pH Scale