Acids and Bases 14
Chapter Overview
What is an acid? Are all acids bad? What is the difference between an acid and a base?
The definitions of acids and bases are given as well as how they interact with one another and
other species. The biological implications and socioeconomic consequences of their reactivity is
also discussed. Calculations involving acid and base reactivity are also performed and explained.
Lecture Outline
14.1 Sour Patch Kids and International Spy Movies
14.2 Acids: Properties and Examples
Learning Objective: Identify common acids and describe their key characteristics.
A. Sour taste
B. Dissolve many metals
C. Turns blue litmus paper red
D. Common acids
1. HCl is hydrochloric acid
3. HNO3 is nitric acid
14.3 Bases: Properties and Examples
Learning Objective: Identify common bases and describe their key characteristics.
A. Bitter taste
B. Feel slippery
C. Turns red litmus paper blue
D. Common bases
2. Sodium hydroxide
14.4 Molecular Definitions of Acids and Bases
Learning Objective: Identify Arrhenius acids and bases.
Learning Objective: Identify Brønsted–Lowry acids and bases and their conjugates.
A. Arrhenius definition
1. Acids produce H+ ions in aqueous solution
B. H+ is actually H3O+
C. Brønsted–Lowry definition
1. Acids are proton (H+ ion) donors
D. Conjugate acid–base pairs
14.5 Reactions of Acids and Bases
Learning Objective: Write equations for neutralization reactions.
Learning Objective: Write equations for the reactions of acids with metals and with metal
oxides.
14.6 Acid-Base Titrations: A Way to Quantify the Amount of Acid or Base in a Solution
Learning Objective: Use acid-base titration to determine the concentration of an unknown
14.7 Strong and Weak Acids and Bases
Learning Objective: Identify strong and weak acids and strong and weak bases.
Learning Objective: Determine [H3O+] in acid solutions.
Learning Objective: Determine [OH–] in base solutions.
A Strong acids are strong electrolytes
14.8 Water: Acid and Base in One
Learning Objective: Calculate [H3O+] or [OH–] from Kw.
A. Amphoteric
B. All aqueous solution contains both H3O+ and OH–
14.9 The pH and pOH Scale: Ways to Express Acidity and Basicity
Learning Objective: Calculate pH from [H3O+].
Learning Objective: Calculate [H3O+] from pH.
Learning Objective: Calculate [OH–] from pOH.
Learning Objective: Compare and contrast the pOH scale and the pH scale.
A. pH = -log[H3O+] ; pOH = -log[OH–]
14.10 Buffers: Solutions That Resist pH Change
Learning Objective: Describe how buffers resist pH change.
14.11 Acid Rain: An Environmental Problem Related to Fossil-Fuel Combustion
A. Damage
B. Legislation
Chemical Principle Teaching Ideas
Properties of Acids and Bases
Give the students an example of real-world acids and bases and ask them to describe the
various properties of them.
Reactions of Acids and Bases
Doing a few demonstrations in class helps, but discussing some acid-base reactions that
pH Scale
There are examples of household chemicals at all pH levels. Bring in samples of each
kind and measure their pH. Emphasize that pH is a logarithmic scale and that if we know the pH
of a solution, we can easily calculate both [H3O+] and [OH–].
Buffers
Buffers can be made from weak acids and their conjugate bases or from a weak base and
Acid Rain
Talking about the history of acid rain and how it is purely a human made problem will
Skill Builder Solutions
14.1. a. H2O loses a H+, so it is the Brønsted–Lowry acid. The conjugate base for H2O is OH–.
14.2. H3PO4 is a triprotic acid, meaning that 1 mol of
34
H PO
requires 3 mol of
OH−
to
14.3. a. The reaction between HCl and Sr metal will form hydrogen gas and a salt. The salt
contains the anion from the acid and the metal ion. Thus, Sr(s) + HCl(aq) →
14.4. The balanced chemical equation is H2SO4(aq) + 2 KOH(aq) → 2 H2O(l) + K2SO4(aq)
14.5. a. HCHO2 is a weak acid, so it does not completely ionize in solution: [H3O+] < 0.5 M
14.6. a. Ba(OH)2 is a strong base, so it completely ionizes in solution. For every one Ba(OH)2
14.7. Kw = [OH–][H3O+] = 1.0 × 10–14 ;
-14
+w
3—
K1.0 10
[H O ] = =
[OH ] [OH ]
14.8. a. pH = -log[H3O+] = – log(9.5 × 10-9 M) = 8.02. With a pH > 7, the solution is basic.
Plus. We must first calculate the [H3O+]:
14.10. pOH = -log[OH–] ; 4.25 = – log[OH–] ; log-1(-4.25) = log-1 (log[OH–]) ;
Suggested Demonstrations
Make up a concentrated solution of baking soda (sodium bicarbonate) and pass it around the
class. Let the students touch it to feel the slippery nature of bases.
Guided Inquiry Ideas
Below are a few example questions that students answer in the guided inquiry activities provided
in the Guided Activity Workbook.
What is the pH of a solution with [H3O+] = 0.01? [H3O+] = 1.0 × 10–7?