Charge-Transfer Reactions:
Acids and Bases and Oxidation-Reduction
Chapter Outline
CHEMISTRY CONNECTION: Drug Delivery
9.1
Acids and Bases
Arrhenius Theory of Acids and Bases
Brønsted-Lowry Theory of Acids and Bases
Conjugate Acids and Bases
Acid-Base Properties of Water
Acid and Base Strength
The Dissociation of Water
9.2
pH: A Measurement Scale for Acids and Bases
A Definition of pH
Measuring pH
Calculating pH
The Importance of pH and pH Control
9.3
Reactions between Acids and Bases
Neutralization
AN ENVIRONMENTAL PERSPECTIVE: Acid Rain
Polyprotic Substances
9.4
Acid-Base Buffers
The Buffer Process
Addition of Base (OH–) to a Buffer Solution
Addition of Acid (H3O+) to a Buffer Solution
Preparation of a Buffer Solution
The Henderson-Hasselbalch Equation
A CLINICAL PERSPECTIVE: Control of Blood pH
9.5
Oxidation-Reduction Processes
A CLINICAL PERSPECTIVE: Oxidizing Agents for Chemical Control of Microbes
Oxidation and Reduction
Applications of Oxidation and Reduction
A CLINICAL PERSPECTIVE: Electrochemical Reactions in the Statue of Liberty and in Dental
Fillings
Biological Processes
Voltaic Cells
A MEDICAL PERSPECTIVE: Turning the Human Body into a Battery
Electrolysis
Summary
Key Terms
Questions and Problems
Critical Thinking Problems
Instructional Objectives
Conceptual Objectives
• Know how to recognize acids and bases and acid-base reactions.
• Describe the role of the solvent in acid-base reactions.
• Know what is meant by the term pH.
• Describe the meaning and utility of neutralization reactions.
• Know the meaning of the term buffer and the application of buffers to chemical and biochemical
systems, particularly blood chemistry.
• Define oxidation and reduction.
Performance Objectives
• Write equations describing acid-base dissociation and label the conjugate acid-base pairs.
• Calculate solution concentration in the commonly used units: weight/volume percent,
volume/volume percent, weight/weight percent, and molarity.
• Calculate pH from concentration data.
• Calculate hydronium and/or hydroxide ion concentration from pH data.
• Describe some practical examples of redox processes.
• Diagram a voltaic cell and describe its function.
• Compare and contrast voltaic and electrolytic cells.
Health Applications
• Provide examples of the importance of pH in chemical and biochemical systems.
• Relate the buffer process to blood pH.
• Describe medical applications that are based on oxidation-reduction processes and
electrochemical cells.
In-Chapter Examples
Example 9.1:
Example 9.2:
Example 9.3:
Example 9.4:
Example 9.5:
Example 9.6:
Example 9.7:
Example 9.8:
Example 9.9:
Example 9.10:
Predicting relative acid-base strengths.
Calculating pH from acid molarity.
Calculating [H3O+] from pH.
Calculating the pH of a base.
Calculating both hydronium and hydroxide ion concentrations from pH.
Calculating pH with non-integer numbers.
Calculating [H3O+] from pH.
Determining the concentration of a solution of hydrochloric acid. (Illustration of a
titration.)
Calculating the pH of a buffer solution.
Calculating the pH of a buffer solution.
Chapter Overview
Acids and Bases
Acids and bases may be described according to either the Arrhenius or Brønsted theory. Acids
increase the hydronium ion concentration of aqueous solutions while bases increase the hydroxide ion
concentration. Water is amphiprotic, meaning that it has both acid and base properties.
The strength of acids and bases in water depends on their degree of dissociation, the extent to which
they react with water. Acids and bases are strong when the reaction with water is virtually 100%
complete and weak when the reaction with water is much less than 100% complete.
Aqueous solutions of acids and bases are electrolytes. Electrolytes are strong or weak depending
upon whether the acid or base in solution is strong or weak.
Neutralization involves the reaction of an acid and a base, resulting in a neutral aqueous salt solution.
A titration is a special application of a neutralization reaction, useful in determining the concentration of
acid or base solution.
The autoionization of water produces a hydronium ion and a hydroxide ion from two water
molecules. The product of the hydronium and hydroxide ion concentrations is a constant, the ion product
for water, and is equal to 1.0 x 10–14. For pure water, both the hydronium ion and the hydroxide ion
concentrations are 1.0 x 10–7 M.
pH: A Measurement Scale for Acids and Bases
The pH scale correlates the hydronium ion concentration with a number, the pH, that serves as a
useful indicator of the degree of acidity or basicity of a solution. The pH of a solution is defined as the
negative logarithm of the molar concentration of the hydronium ion (pH = –log[H3O+]).
Acid-Base Buffers
Buffer solutions, consisting of a mixture of a weak acid and its salt or a weak base and its salt, are
resistant to large pH changes upon the addition of acids or bases. Buffer solutions follow LeChatelier's
principle. An important application of buffers involves regulation blood pH in the human body.
A buffer solution can be described by an equilibrium-constant expression, which can be used to
calculate the hydronium ion concentration to obtain the pH. Alternatively, the Henderson-Hasselbalch
equation may be used.
Oxidation - Reduction Processes
Oxidation is defined as a loss of one or more electrons, loss of hydrogen atoms, or gain of oxygen
atoms. Reduction is defined as a gain of one or more electrons, gain of hydrogen atoms, or loss of oxygen
atoms. Oxidation and reduction are complementary processes. The combination of the oxidation halfreaction and the reduction half-reaction produces the complete reaction.
The reducing agent releases electrons for the reduction of a second substance to occur. The oxidizing
agent accepts electrons, causing the oxidation of a second substance to take place.
A voltaic cell is an electrochemical cell that converts chemical energy into electrical energy.
Electrolysis is the opposite of a battery. It converts electrical energy into chemical potential energy.
Hints for Faster Coverage
The primary material in the chapter deals with the chemistry of acids and bases. If the class has a
reasonable background, some of sections 9.1 and 9.2 may be presumed.
Suggested Problem Sets
Acids and Bases: 25, 27, 29, 31, 33, 35, 37
pH of Acid and Base Solutions: 39, 41, 43, 45, 47, 49, 51, 53, 55, 57
Buffer Solutions: 59, 61, 63, 65
Oxidation - Reduction Reactions: 67, 69, 71, 73, 75, 77
In-Chapter Perspectives
AN ENVIRONMENTAL PERSPECTIVE: Acid Rain. This perspective ties a worsening global
environmental problem, acid rain, to the discussion of the behavior of acids, bases, and buffers in aqueous
solution.
A CLINICAL PERSPECTIVE: Control of Blood pH. A practical application of buffers, pH balance in
our blood, is discussed.
A CLINICAL PERSPECTIVE: Oxidizing Agents for Chemical Control of Microbes. This perspective
discusses the role of oxidation-reduction chemistry in combating a major medical problem: the
uncontrolled growth of infectious organisms.
A CLINICAL PERSPECTIVE: Electrochemical Reactions in the Statue of Liberty and in Dental Fillings.
This perspective uses two commonly-known phenomena and describes them in the context of oxidationreduction concepts learned in this chapter.
A MEDICAL PERSPECTIVE: Turning the Human Body into a Battery. A current area of medical
research involving electrochemical principles is discussed.
Additional Perspectives
Many drug formulations contain acids or bases (such as antacids). The acidity of aspirin and its effect
on the lining of the stomach are well-known. The reactivity of drugs is often dependent upon its acid-base
properties. Any of these ideas may be expanded to help to relate acid-base chemistry to the "real world."
Critical Thinking Problems
1.
Students are expected to use library resources to broaden their understanding of heavy metal
pollution, acid rain, and their interaction. Students may discover the importance of oxidation state in
metal toxicity. They may find, for example, that Cr(VI) is much more of an environmental concern
than Cr(III).
2.
The students will follow up on Question 1., seeing more evidence that pH and solubility are related.
3.
The students must integrate Lewis structures and acid-base theory to answer this question. The
instructor may wish to introduce Lewis acid-base theory into the discussion.
4.
This question introduces the students to some practical acid-base applications.
5.
The scope of environmental problems and their relationship to fundamental chemical reactions can
be a useful discussion topic introduced with this question.
Chapter 9
Charge-Transfer Reactions:
Acids and Bases and Oxidation-Reduction
Solutions to the Even-Numbered Problems
In-Chapter Questions and Problems
9.2
9.4
a.
HBr(aq) + H2O(l)
H3O+ (aq) + Br–(aq)
b.
H2S(aq) + H2O(l)
H3O+ (aq) + HS–(aq)
a.
HBr and Br–; H2O and H3O+
H2S and HS–; H2O and H3O+
9.6
a.
PO43–; based on Figure 9.2
HPO42-; based on Figure 9.2
9.8
A 1.0 x 10-5 M NaOH solution corresponds to a pH = 9.00
(Example 9.4).
A solution of sodium hydroxide with a pH = 10.00 corresponds to a NaOH concentration of 1.0
x 10-4M. Therefore, [OH–] must be 1.0 x 10-4M. Recalling that
[H3O+][OH–] = 1.0 x 10-14
[H3O+] =
1.0 x 10 -14
-
[OH ]
=
1.0 x 10 14
1.0 x 10
-4
= 1.0 x 10 -10 M
9.10
Referring to the discussion of the decimal-based system, a solution of sodium hydroxide with
[OH–] = 1.0 x 10-5 M corresponds to a pH of 9.00.
9.12
A pH of 4.50 is a non-integer. The calculation of the [H3O+] is most easily accomplished with
the aid of a calculator.
pH = –log [H3O+]
and, [H3O+] = 10-pH
On the calculator:
Enter 4.50
Press "Change sign" key
Press 10x key
The result is [H3O+] = 3.16 x 10-5 M
9.14
The acid-base reaction is:
HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
(Macid) (Vliters acid) = (Mbase) (Vliters base)
Solving for Mbase,
Mbase =
(Macid )(Vliters acid )
(Vliters base )

1 L 
(0.2000 M) 25.00 ml x

10 3 mL  = 0.1389 M
Mbase =

1 L 
36.00 ml x

10 3 mL 
9.16
The equilibrium reaction is:
CO2 + H2O
H2CO3
H3O+ + HCO3-
A decrease in the partial pressure of CO2 is a stress on the left side of the equilibrium. The
equilibrium will shift to the left in an effort to increase the concentration of CO 2. This will
cause the molar concentration of H2CO3 to decrease.
9.18
The equilibrium reaction is:
CO2 + H2O
H3O+ + HCO3-
H2CO3
In question 9.13, the equilibrium shifts to the right and [H 3O+] increases. If [H3O+] increases,
the pH decreases (remember that a large [H3O+] corresponds to a low pH.)
In Question 9.15, the equilibrium shifts to the left and [H 3O+] decreases. If [H3O+] decreases,
the pH increases (remember that a low [H3O+] corresponds to a high pH.)
9.20
Propanoic acid is the acid; [acid] = [2.00 x 10 -1]
Sodium propanoate is the conjugate base;
[conjugate base] = 2 x 2.00 x 10-1 (remember, the salt concentration is doubled)
The equilibrium is:
C2H5COOH(aq) + H2O(l)
acid
H3O+(aq) + C2H5COO–(aq)
conjugate base
and the hydronium ion concentration =
[H 3O ] =
+
[C2 H5 COOH]Ka
[C 2H 5COO – ]
Substituting the values given in the problem
[H 3O + ] =
[2.00 x 10 -1](1.34 x 10 -5)
-1
[4.00 x 10 ]
= 6.70 x 10 -6
and since
pH = –log [H3O+]
pH = log (6.70 x 10-6)
pH = 5.17
9.22
[acid] = 2.00 x 10-1 M
[conjugate base] = 1.00 x 10-1 M
Ka = 1.75 x 10-5
pKa = –log Ka
pKa = –log(1.75 x 10-5)
pKa = 4.76
Henderson-Hasselbalch equation: pH = pKa + log
Substituting,
pH = 4.76 + log
1.00 x 10 1 M
2.00 x 10 1 M
[conjugate base]
[weak acid]
pH = 4.46
9.24
[acid] = 2.00 x 10-1 M
[conjugate base] = 4.00 x 10-1 M
Ka = 1.34 x 10-5
pKa = –log Ka
pKa = –log(1.34 x 10-5)
pKa = 4.87
Henderson-Hasselbalch equation: pH = pKa + log
Substituting,
pH = 4.87 + log
[conjugate base]
[weak acid]
4.00 x 10 1 M
2.00 x 10 1 M
pH = 5.17
End-of-Chapter Questions and Problems
9.26
a.
An Arrhenius base is a substance that dissociates, producing hydroxide ions.
b.
A Brønsted-Lowry base is a substance that behaves as a proton acceptor.
9.28
Ammonia is not described as an Arrhenius base because it cannot dissociate to produce an OH –.
However, it can act as a proton acceptor, or Brønsted-Lowry base:
NH3(aq) + H2O(l)
NH4+(aq) + OH–(aq)
9.30
a.
HNO3(aq) + H2O(l)  H3O+(aq) + NO3–(aq)
b.
HCOOH (aq) + H2O(l)
a.
HNO3 and NO3– ; H2O and H3O+
9.32
H3O+(aq) + HCOO–(aq)
HCOOH and HCOO–; H2O and H3O+
9.34
a.
KOH is a strong base.
b.
CN– is a weak base.
c.
SO42– is a weak base.
a.
HCOOH and HCOO–; NH3 and NH4+
b.
HCl and Cl–; OH– and H2O
9.38
a.
b.
c.
d.
a concentrated strong acid: II
a dilute strong acid: III
a concentrated weak acid: I
a dilute weak acid: IV
9.40
[H3O+] [OH–] = 1.0 x 10-14
9.36
[H 3O + ] =
Solving for [H3O+],
a.
+
+
9.44
1 x 10 -14
1.0 x 10
= 1.0 x 10
–9
–5
M
–9
M
Substituting [OH-] = 1.0 x 10-5 M
[H 3O ] =
9.42
[OH– ]
Substituting [OH-] = 1.0 x 10-9 M
[H 3O ] =
b.
1 x 10 -14
1 x 10 -14
1.0 x 10
= 1.0 x 10
–5
a.
Acidic, [H3O+] is greater than 1.0 x 10-7M
b.
Basic, [H3O+] is less than 1.0 x 10-7M
a.
pH = –log [H3O+]
pH = –log [1.0 x 10-10]
pH = 10.00
b.
pH = –log [H3O+]
Since [H3O+] [OH–] = 1.0 x 10-14
and,
[H 3O + ] =
Substituting,
1 x 10 -14
[OH– ]
+
[H 3O ] =
1 x 10 -14
1.0 x 10
–5
and, pH = –log [1.0 x 10-9]
pH = 9.00
9.46
a.
pH = –log [H3O+]
and, [H3O+] = 10-pH
On your calculator:
Enter 5.00
Press "change sign" key
Press 10x key
The result is [H3O+] = 1.0 x 10-5M
and, [H3O+] [OH–] = 1.0 x 10-14
= 1.0 x 10
–9
M
solving for [OH–]
1.0 x 10 -14
[OH – ] =
b.
+
[H3 O ]
=
1.0 x 10 -14
1.0 x 10
–5
= 1.0 x 10 –9 M
pH = –log[H3O+]
and, [H3O+] = 10-pH
On the calculator:
Enter 7.20
Press "change sign" key
Press 10x key
The result is [H3O+] = 6.3 x 10-8M
and, [H3O+] [OH–] = 1.0 x 10-14
solving for [OH–]
1.0 x 10 -14
[OH – ] =
+
[H3 O ]
=
1.0 x 10 -14
6.3 x 10
–8
= 1.6 x 10 –7 M
pH = –log[H3O+]
9.48
and, [H3O+] = 10-pH
On the calculator:
Enter 5.50
Press "change sign" key
Press 10x key
The result is [H3O+] = 3.2 x 10-6M
and, [H3O+] [OH–] = 1.0 x 10-14
solving for [OH–]
[OH – ] =
b.
1.0 x 10 -14
+
[H3 O ]
=
1.0 x 10 -14
3.2 x 10
pH = –log [H3O+]
and, [H3O+] = 10-pH
On the calculator:
Enter 7.00
Press "change sign" key
Press 10x key
The result is [H3O+] = 1.0 x 10-7M
–6
= 3.2 x 10 –9 M
and, [H3O+] [OH–] = 1.0 x 10-14
solving for [OH–]
[OH – ] =
1.0 x 10 -14
+
[H3 O ]
=
1.0 x 10 -14
1.0 x 10
–7
= 1.0 x 10 –7 M
9.50
A titration is a commonly used method for chemical analysis. A base of unknown concentration
is titrated with a solution of standard acid. The concentration of the base can be calculated from
the molarity and volume of the standard solution and the volume of the unknown base solution.
Conversely, the concentration of an unknown acid can be determined by titration with standard
base.
9.52
Patient A:
pH = –log [H3O+]
pH = –log [5.0 x 10-8]
pH = 7.30
pH = –log [H3O+]
Patient B:
pH = –log [3.1 x 10-8]
pH = 7.51
pH = –log [H3O+]
Patient C:
pH = –log [3.2 x 10-8]
pH = 7.49
If the normal pH range for blood is 7.30 - 7.50, patient B would be considered just outside of the
normal range. Patients A and C would be within the normal range.
9.54
9.56
One pH unit difference corresponds to a tenfold difference in concentration of H 3O+ or OH–.
a.
b.
c.
6 - 4 = 2 pH units  102 fold = 100 fold.
10 - 9 = 1 pH unit  101 fold = 10 fold.
11 - 6 = 5 pH units  105 fold = 100,000 fold.
a.
pH = 5.0
[H3O+] = 1.0 x 10–5 M
–
[OH ] =
b.
+
[H3 O ]
=
1.0 x 10 -14
1.0 x 10
–5
= 1.0 x 10 –9 M
pH = 12.0
[H3O+] = 1.0 x 10–12 M
[OH – ] =
c.
1.0 x 10 -14
1.0 x 10 -14
+
[H3 O ]
pH = 5.50
[H3O+] = 3.16 x 10–6 M
=
1.0 x 10 -14
1.0 x 10
–12
= 1.0 x 10 –2 M
[OH – ] =
9.58
9.60
9.62
9.64
a.
[OH – ] =
b.
[OH – ] =
–
1.0 x 10 -14
+
[H3 O ]
1.0 x 10 -14
+
[H3 O ]
1.0 x 10 -14
+
[H3 O ]
1.0 x 10 -14
=
=
=
3.16 x 10
–6
1.0 x 10 -14
1.0 x 10
–6
1.0 x 10 -14
1.0 x 10
–8
1.0 x 10 -14
= 3.16 x 10 –9 M
= 1.0 x 10 –8 M
= 1.0 x 10 –6 M
= 1.8 x 10 –11 M
c.
[OH ] =
a.
HBr is a weak acid. However, MgCl2, although a salt, is not formed from HBr.
Consequently these substances would not form a suitable buffer solution.
b.
H2CO3 is a weak acid. NaHCO3 is a salt formed from H2CO3. Consequently, H2CO3 and
NaHCO3 can form a buffer solution.
a.
Alkalosis is a medical condition characterized by lower-than-normal levels of CO2 in the
blood and higher-than-normal blood pH.
b.
A standard solution is one whose concentration is known with certainty.
a.
Addition of a strong base will be equivalent to decreasing [H 3O+] since
+
[H3 O ]
=
1.0 x 10 -14
5.6 x 10
–4
OH–(aq) + H3O+(aq)  2H2O.
Decreasing [H3O+] is a stress on the right side of the equilibrium. The equilibrium will
shift to the right to make CH3COO– and more H3O+ to alleviate the stress.
b.
Adding acetic acid to the solution places a stress on the left side of the equilibrium;
[CH3COOH] increases. Consequently, the equilibrium shifts to the right to reduce the
stress, forming CH3COO– and H3O+.
9.66
In question 9.65 we found that [H3O+] = 2.32 x 10-7 M
Since
pH = –log [H3O+]
pH = –log 2.32 x 10-7
pH = 6.63
9.68
a.
Reduction is defined as the gain of electrons, gain of hydrogen atoms or loss of oxygen
atoms.
b.
A reducing agent donates electrons to another substance. In doing this the reducing agent
becomes oxidized.
9.70
During an oxidation-reduction reaction the species reduced is the oxidizing agent.
9.72
Metals tend to be good reducing agents.
9.74
9.76
9.78
Zn
substance oxidized
reducing agent
+
Cu2+
substance reduced
oxidizing agent

Zn2+
+ Cu
A battery and an electrolysis cell are both electrochemical cells. Their function is based on
oxidation-reduction processes. A battery converts stored chemical energy to electrical energy (a
current flow) whereas electrolysis uses electrical energy to bring about chemical change.
Electrolytic cells are widely used in industry to electroplate metals, creating a more desirable
surface. Common examples include silver plating and chrome plating. Rechargable batteries,
used in many appliances, constitute another major application.
1. Which theory describes an acid as a proton donor and a base as a
proton
acceptor?
2. What is another name for a protonated water molecule?
3. Explain briefly what is meant by a "conjugate acid-base pair" in
the
Brønsted-Lowry theory. Give an example of such a pair.
4. What is the conjugate acid of NH3?
5. What is the conjugate base of HNO3?
6. What is the fundamental difference between a strong acid and a weak
acid?
7. Complete the following equation for the dissociation of acetic acid
in
water, so as to illustrate unambiguously that acetic acid is a weak
acid:
CH3COOH(aq) + H2O(l)
8. What is meant by the "auto-ionization of water"?
9. In a chemical context, what is meant by the term "neutralization"?
10. What do we call a substance which is used to show changes in pH by
its
change in color?
11. What is the name of the process in which we carefully measure the
volume of a solution of known concentration needed to neutralize a
solution of unknown concentration?
12. What is meant by a diprotic acid? Give an example.
13. Consider the following generalized buffer solution equilibrium:
BH+(aq) + H2O(l) H3O+(aq) + B(aq)
If a small amount of a strong base such as sodium hydroxide is added
to
the above buffer solution, which of the four species shown would
increase in concentration? (Hint: Use LeChatelier's principle.)
14. What is meant by the "buffer capacity" of a solution?
15. Given a particular buffer solution consisting of a weak acid and
its
salt, how would you modify it so as to increase its buffer capacity
against base?
16. A buffer solution contains carbonic acid (H2CO3) and sodium
bicarbonate
(NaHCO3), each at a concentration of 0.100 M. The relevant equilibrium
is:
H2CO3(aq) + H2O(l) H3O+(aq) + HCO3-(aq) with Ka = 4.5 10-7
Calculate the pH of this solution.
17. What is the name of the condition in which the carbon dioxide
level in
the blood is lower than normal?
Page 1
18. What is the general term for the process in which a chemical
species
gains electrons?
19. What is the general term for processes such as the conversion of
sodium
atoms to sodium ions?
20. Briefly explain what is meant by a "voltaic cell" and an
"electrolytic
cell", emphasizing how they relate to one another.
21. In a voltaic cell, oxidation occurs at the ______ while reduction
occurs at the ______.
22. Who gave us the earliest definitions of acids and bases?
A. Arrhenius
B. Brønsted
C. Lewis
D. Lowry
E. LeChatelier
23. Which one of the following is NOT generally true of a base?
A. tastes bitter
B. feels slippery
C. increases [H+] in water
D. is corrosive
E. causes many metal ions to precipitate
24. Which one of the following pairs is a conjugate acid-base pair?
A. H2O, OB.
H3O+, OHC.
HCO3-, CO32D. HCl, Cl
E. NaOH, Na+
25. What is the hydronium ion concentration of pure water at 25C?
A. 7.0 107
B. 7.0 10-7
C. 1.0 107
D. 1.0 10-7
E. 1.0 10-14
26. If the hydronium ion concentration of an aqueous solution at 25°C
is
5 10-6 M, what is the hydroxide ion concentration?
A. 2 10-10
B. 2 10-9
C. 2 10-8
D. 2 107
E. 2 1019
Page 2
27. What is the hydronium ion concentration of a solution with a pH of
6.0?
A. 1 106
B. 1 10-6
C. 6 101
D. 6 10-1
E. 6 10-14
28. What is the pH of a 1.0 10-4 M solution of KOH?
A. 4.00 B. 6.00 C. 7.00 D. 10.00 E. 14.00
29. What is the pH of a solution that has [H3O+] = 6.0 10-3 M?
A. 1.7 10-12
B. 2.22
C. 3.60
D. 5.12
E. 11.78
30. If 14.8 mL of 0.100 M NaOH solution are needed to react with 25.0
mL of
an unknown HCl solution, what is the molar concentration of the HCl
solution?
A. 0.592 M
B. 5.87 M
C. 0.0592 M
D. 0.0692 M
E. 1.25 M
31. The reaction of an acid with a base will produce a salt. What is
the
other product?
A. a hydronium ion
B. water
C. a buffer
D. a metal
E. a hydroxide ion
32. What word is used to describe a solution that contains a conjugate
acid-base pair and is resistant to large changes in pH?
A. indicator
B. saturated
C. buffer
D. standard
E. resistive
Page 3
33. What particle is transferred from one reactant to another in
oxidationreduction
reactions?
A. proton
B. electron
C. hydronium ion
D. hydrogen ion
E. hydride ion
34. What term describes a reactant that removes electrons from another
reactant?
A. oxidizing agent
B. reducing agent
C. buffer
D. base
E. anode
35. Identify the oxidizing agent and reducing agent, respectively, in
the
following reaction:
Cl2(aq) + 2I-(aq) 2Cl-(aq) + I2(aq)
A. Cl2 and IB.
I- and Cl2
C. Cl- and I2
D. I2 and ClE. Cl2 and Cl36. Which one of the following substances is not a good oxidizing
agent?
A. hydrogen peroxide
B. sodium hypochlorite
C. chlorine
D. ozone
E. carbon dioxide
37. Which of the following words best describes the general type of
process
occurring at the cathode of a voltaic cell?
A. corrosion
B. combustion
C. electrolysis
D. reduction
E. oxidation
38. T F According to Arrhenius's theory, all acids increase the
hydrogen
ion concentration in water.
39. T F All Brønsted-Lowry acids must contain hydrogen.
40. T F All Brønsted-Lowry bases must contain hydroxide
41. T F In any conjugate acid-base pair, at least one of the species
must
carry a charge.
Page 4
42. T F Acetic acid dissociates completely when dissolved in water.
43. T F Strong acids are almost completely dissociated in water.
44. T F All strong bases are metal hydroxides.
45. T F The concentration of a weak acid or base does NOT affect the
degree of dissociation.
46. T F The ion-product of water is NOT affected by a change in
temperature.
47. T F A pH of 0 is considered neutral.
48. T F A standard solution is a solution whose concentration is
accurately known.
49. T F Carbonic acid and the bicarbonate ion form the main buffer
system
found in blood.
50. T F A weak acid plus the salt of a strong acid, in water, will
form a
buffer solution.
51. T F All buffer solutions operate at a pH close to 7.
52. T F Emphysema can cause blood acidosis.
53. T F The reducing agent is oxidized during a oxidation-reduction
reaction.
54. T F The conversion of ferrous ion to ferric ion is a reduction
reaction.
55. T F The conversion of Fe2+ to Fe3+ is a reduction reaction.
56. T F Metals such as sodium are good reducing agents.
57. T F A rechargeable battery can operate either as a voltaic cell or
as
an electrolytic cell.
58. T F In electrolysis, electrical energy is used to drive a
nonspontaneous
chemical reaction.
Page 5
Answer Key for Test "chapter9.tst", 8/17/04
No. in
Q-Bank
No. on
Test Correct Answer
9 1 1 Brønsted-Lowry theory
9 2 2 hydronium ion
9 3 3 According to this theory, an acid donates a proton and in the
process becomes a base. Thus, a conjugate acid-base pair is a
pair of species which differ by one proton. e.g., H2O and OH-.
9 4 4 NH4+
9 5 5 NO39 6 6 A strong acid dissociates completely in solution. A weak acid
dissociates only partially, forming relatively fewer hydronium
ions than a strong acid.
9 7 7 CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq)
9 8 8 It is the transfer of a proton from one water molecule to
another, producing a hydronium ion and a hydroxide ion.
9 9 9 The reaction between an acid and a base.
9 10 10 an indicator
9 11 11 titration
9 12 12 A diprotic acid is capable of donating two protons. e.g.,
H2SO4
9 13 13 B(aq)
9 14 14 Buffer capacity refers to the amount of added acid or base
which
the buffer solution can neutralize without undergoing a
substantial change in pH.
9 15 15 increase the concentration of the weak acid
9 16 16 6.35
9 17 17 alkalosis
9 18 18 reduction
9 19 19 oxidation
9 20 20 A voltaic cell utilizes a spontaneous oxidation-reduction
reaction to produce electrical energy; an electrolytic cell
reverses this process, using electrical energy to drive a
nonspontaneous
oxidation-reduction reaction.
9 21 21 anode, cathode
9 22 22 A
9 23 23 C
9 24 24 C
9 25 25 D
9 26 26 B
9 27 27 B
9 28 28 D
9 29 29 B
9 30 30 C
9 31 31 B
9 32 32 C
9 33 33 B
9 34 34 A
9 35 35 A
9 36 36 E
9 37 37 D
9 38 38 T
9 39 39 T
9 40 40 F
9 41 41 T
9 42 42 F
Page 1
Answer Key for Test "chapter9.tst", 8/17/04
No. in
Q-Bank
No. on
Test Correct Answer
9 43 43 T
9 44 44 T
9 45
9 46
9 47
9 48
9 49
9 50
9 51
9 52
9 53
9 54
9 55
9 56
9 57
9 58
Page
45
46
47
48
49
50
51
52
53
54
55
56
57
58
2
F
F
F
T
T
F
F
T
T
F
F
T
T
T
The Nucleus, Radioactivity, and Nuclear Medicine
Chapter Outline
CHEMISTRY CONNECTION: An Extraordinary Woman in Science
10.1
Natural Radioactivity
Alpha Particles
Beta Particles
Gamma Rays
Properties of Alpha, Beta, and Gamma Radiation
10.2
Writing a Balanced Nuclear Equation
Alpha Decay
Beta Decay
Gamma Production
Predicting Products of Nuclear Decay
10.3
Properties of Radioisotopes
Nuclear Structure and Stability
Half-Life
10.4
Nuclear Power
Energy Production
Nuclear Fission
Nuclear Fusion
Breeder Reactors
10.5
Radiocarbon Dating
10.6
Medical Applications of Radioactivity
AN ENVIRONMENTAL PERSPECTIVE: Nuclear Waste Disposal
Cancer Therapy Using Radiation
Nuclear Medicine
Making Isotopes for Medical Applications
10.7
Biological Effects of Radiation
Radiation Exposure and Safety
A CLINICAL PERSPECTIVE: Magnetic Resonance Imaging
10.8
Measurement of Radiation
Nuclear Imaging
Computer Imaging
The Geiger Counter
Film Badges
AN ENVIRONMENTAL PERSPECTIVE: Radon and Indoor Air Pollution
Units of Radiation Measurement
Summary
Key Terms
Questions and Problems
Critical Thinking Problems
Instructional Objectives
Conceptual Objectives
• Know what is meant by the term radioactivity.
• Know the characteristics of alpha, beta, and gamma radiation.
• Distinguish between natural and artificial radioactivity.
• Know what is meant by the term half-life, and understand its importance.
• Familiarize yourself with common techniques for the detection of radioactivity.
• Develop an understanding of the common units in which radiation intensity is represented: the
curie, the roentgen, the rad, and the rem.
Performance Objectives
• Explain why only certain isotopes of an element are radioactive.
• Write balanced equations for common nuclear processes.
• Calculate the amount of radioactive substance remaining after a specified number of half-lives.
• Describe the various ways in which nuclear energy may be used to generate electricity: fission,
fusion, and the breeder reactor.
• Explain the process of radiocarbon dating.
Health Applications
• Cite several examples of the use of radioactive isotopes in medicine.
• Discuss the biological effects of radiation.
• Describe the use of ionizing radiation in cancer therapy.
• Discuss the preparation of radioisotopes for use in diagnostic imaging studies.
• List the advantages of MRI over conventional X-ray diagnosis.
In-Chapter Examples
Example 10.1:
Example 10.2:
Predicting the products of radioactive decay.
Predicting the extent of radioactive decay.
Chapter Overview
Natural Radioactivity
Radioactivity is the process by which atoms emit radiation - energetic, ionizing particles or rays.
Nuclear radiation occurs because the nucleus is unstable, i.e., radioactive. Nuclear symbols consist of the
elemental symbol, the atomic number, and the mass number.
Not all nuclei are unstable. Only unstable nuclei undergo radioactive decay. Three types of natural
radiation emitted by unstable nuclei are alpha particles, beta particles, and gamma rays. This radiation is
collectively termed ionizing radiation.
Writing a Balanced Nuclear Equation
A nuclear equation represents a nuclear process such as radioactive decay. The total of the mass
numbers on each side of the reaction arrow must be identical, and the sum of the atomic numbers of the
reactants must equal the sum of the atomic numbers of the products. Nuclear equations can be used to
predict products of nuclear reactions.
Properties of Radioisotopes
Not all nuclei are equally stable, nor do they decay at the same rate. Products of decay differ from
isotope to isotope as does the magnitude of radioactivity emitted.
Binding energy is the energy that holds nuclear particles together in the nucleus. When an isotope
decays, some of this binding energy is released. Nucelar stability correlates with the ratio of neutrons to
protons in the isotope. Nuclei with large numbers of protons tend to be unstable, and isotopes containing
2, 8, 20, 50, 82, or 126 protons or neutrons (magic numbers) are stable. Also, isotopes with even numbers
of protons or neutrons are generally more stable than those with odd numbers of protons or neutrons.
The rate of decay, and thus the degree of nuclear stability, is indicated by the isotope's half-life.
Isotopes with short half-lives decay very rapidly and are very unstable. Each isotope has its own
characteristic half-life.
Nuclear Power
Einstein predicted that a small amount of nuclear mass would convert to a very large amount of
energy when the nucleus breaks apart. Fission reactors are used to generate electrical power.
Technological problems with fusion and breeder reactors have prevented their commercialization in the
United States.
Radiocarbon Dating
Radiocarbon dating is based on the measurement of the relative amounts of C-12 and C-14 present in
an object. The ratio of the masses of these isotopes changes slowly over time, making it useful in
determining the age of objects containing carbon.
Medical Applications of Radioactivity
The use of radiation in the treatment of various forms of cancer, and in the newer area of nuclear
medicine, has become widespread in the past quarter century. Ionizing radiation causes changes in
cellular biochemical processes that may damage or kill the cell. A cancerous organ is composed of both
healthy and malignant cells. Exposure of the tumor area to controlled dosages of high-energy gamma
radiation from cobalt-60 will kill a higher percentage of abnormal cells than normal cells and is a
valuable cancer therapy.
The diagnosis of a host of biochemical irregularities or diseases has been made routine through the
use or radioactive tracers, small amounts of radioactive substances that are used as probes to study
internal organs. Because the isotope is radioactive, its path may be followed by using suitable detection
devices.
Artificial radioactivity is the conversion of a normally stable, nonradioactive nucleus into one that is
radioactive; artificial radioactivity produces synthetic isotopes. Synthetic isotopes are often used in
clinical situations. Isotopic synthesis may be carried out in the core of a nuclear reactor or in a particle
accelerator. Short-lived isotopes, such as technetium-99m, are often produced directly at the site of the
clinical testing.
Biological Effects of Radiation
Safety considerations are based on the magnitude of the half-life, shielding, distance from the
radioactive source, time of exposure, and type of radiation emitted. We are never entirely free of the
effects of radioactivity. Background radiation is normal radiation attributable to our surroundings.
Virtually all applications of nuclear chemistry create radioactive waste and, along with it, the
problems of safe handling and disposal. Most disposal sites are considered temporary, until a long-term
safe solution can be found.
Measurement of Radiation
The changes that take place when radiation interacts with matter provide the basis for various
radiation detection devices. Photographic imaging, computer imaging, the Geiger counter, and film
badges represent the most frequently used devices for detecting and measuring radiation.
Commonly used radiation units include the curie, the roentgen, the rad, and the rem. The lethal dose
of radiation, LD50, is defined as the dose that would be fatal for 50% of the exposed population within
thirty days.
Hints for Faster Coverage
Calculations involving half-life may be omitted. Units of radiation may be excluded or briefly
mentioned. If the career goals of the students in this course are primarily health and medically oriented,
the topics entitled nuclear power and radiocarbon dating (Section 10.4 and 10.S) may be omitted.
Suggested Problem Sets
Natural Radioactivity - 13, 15, 17, 19, 21, 23
Writing a Balanced Nuclear Equation - 25, 27, 29, 31
Properties of Radioisotopes - 33, 35, 37, 39
Nuclear Power - 41, 43, 45, 47, 49, 51
Radiocarbon Dating - 53
Medical Applications of Radioactivity - 55, 57, 59
Biological Effects of Radiation - 61, 63
Measurement of Radiation - 65, 67, 69
In-Chapter Perspectives
AN ENVIRONMENTAL PERSPECTIVE: Nuclear Waste Disposal. This perspective deals with an
increasingly serious side-effect of the growth of nuclear technology - what to do with the waste. The
instructor may wish to emphasize that we have no control over the rate of nuclear decay, in contrast to
conventional chemical reactions.
A CLINICAL PERSPECTIVE: Magnetic Resonance Imaging. This perspective outlines the
development of nuclear magnetic resonance to study hydrogen-containing molecules and its application
to diagnosis of disease using MRI.
A HUMAN PERSPECTIVE: Radon and Indoor Air Pollution. The human, environmental, and
economic consequences of radon pollution may form a basis for the instructor to link the theory of
nuclear reactions with everyday life.
Additional Perspectives
Approximately 20 million nuclear medicine procedures are performed each year in the United States. A
useful discussion in conjunction with this chapter could involve:
 risk/benefit analysis for the patient
 protection for the health care workers
 disposal of the waste radioactive material
 the way in which the radioactive material is made (mention the cyclotron and other, smaller sources).
Critical Thinking Problems
1.
The similarity in chemical behavior is a concept that is fundamental to several applications discussed
in later chapters; examples include medical tracers (Chapter 10) and the elucidation of DNA
replication (Chapter 24).
2.
This problem emphasizes the fundamental differences between chemical and nuclear reactions. It
also will motivate students to think about one of society's significant problems.
3.
This problem is a follow-up to problems 2. and may be useful as a class discussion topic.
4. and 5. The students will discover that a knowledge of structure allows logical prediction of events.
6.
Problems of this type are a useful exercise and are illustrative of the ways that mechanisms (Chapter
13) of organic reactions are deduced.
Chapter 10
The Nucleus, Radioactivity, and Nuclear Medicine
Solutions to the Even-Numbered Problems
In-Chapter Questions and Problems
10.2
Gamma radiation is the highest energy radiation in the electromagnetic spectrum. [See Chapter
2, An Environmental Perspective: Electromagnetic Radiation and its Effects on our Everyday
Lives, for more information.]
10.4
a.
239
92 U
b.
11
5B
10.6


239
93Np
7
3 Li
+
+
0
-1e
4
2 He
The half-life of technetium-99 is 6 hours.
The number (n) of half-lives elapsed is:
n = 1 day x
24 hours
1 half - life
x
1 day
6 hours
= 4 half - lives
Then,
first half -life
10 ng 

 5 ng
second half -life


 2.5 ng
third half-life


1.25 ng
fourth half-life
0.63 ng
Therefore, 0.6 ng (1 sig. fig.) of technetium-99 m remains after one day.
10.8
The half-life of barium-131 is 11.6 minutes.
Then, assume that the original amount is x grams. After the first half-life, x/2 grams remain;
after the second half-life, x/4 grams remain. So, 1/4 of the barium-131 will remain after 2 halflives. Two half lives correspond to 23.2 minutes:
2 half - lives x
11.6 minutes
1 half - life
= 23.2 minutes
10.10
Short half-life substances cannot be stored for long periods of time; they must be used shortly
after manufacture, before their activity becomes too low. Also, the short half-life substance may
expose the patient to a greater quantity of radiation than a longer-lived isotope, assuming that
both isotopes are efficiently removed from the body through biological processes.
10.12
The roentgen is not used in the measurement of alpha radiation. The roentgen measures ionizing
radiation; alpha emission is not ionizing radiation.
End-of-Chapter Questions and Problems
10.14
10.16
a.
An alpha particle is composed of two protons and two neutrons. It is identical to the nucleus
of a helium atom.
b.
Alpha decay is the release of alpha particles from an unstable nucleus.
a.
Beta decay is the release of beta particles from an unstable nucleus. A beta particle is a high
energy electron.
b.
Artificial radioactivity is radiation that results from the conversion of a stable nucleus into
another nucleus that is unstable.
10.18
a.
1
1p
b.
235
92 U
10.20
a.
15
7N
b.
14
6C
10.22
Size:  >  ( has no size; it is electromagnetic radiation.)
Speed:  >  > 
Penetrating power:  >  > 
10.24
Gamma radiation has great penetrating power, high energy, no mass and no charge. Beta
radiation has less penetrating power, lower energy, the mass equal to that of an electron, and a
charge of –1.
10.26
226
88 Ra
10.28
238
92 U

+
222
86 Rn
14
7N

+
4
4
2 He ; 2 He is the -particle
246
99 Np
1
+ 6 0n
[Note the coefficient "6". 238 + 14 = 246 + (6 x 1)]
10.30
186
76Os
10.32
218
92 U
10.34
Fission of uranium-235 is an example of artificial radioactivity; the fission process is not
spontaneous - it must be induced. The products of the reaction include new radioactive
substances.
10.36
The nucleus is made up of neutral and positively charged particles. Owing to the high density of
the nucleus, these particles must be quite close together. A large binding energy must be present
to overcome the repulsion of the like-charged particles.
10.38
The number (n) of half-lives elapsed is:
n = 2.0 days x
Then,
24 hours
1 half - life
x
= 4.0 half - lives
1 day
12 hours
first half -life
10 ng 

 5 ng
second half -life


 2.5 ng
third half-life


1.25 ng
fourth half-life
0.63 ng
Therefore, 0.63 ng of the isotope remain after 2.0 days.
10.40
The half-life of cobalt-60 is 5.3 years.
The time elapsed from the date of manufacture to the year 2010 is:
2010 years - 1978 years = 32 years
The number (n) of half lives elapsed is:
n = 32 years x
1 half - life
= 6.0 half-lives
5.3 years
Then, assuming x g of cobalt-60 originally present,
first
half  life
second
x
x
half  life
x g 


g 


g
2
4
third
fourth
x
x
x
half  life
half  life
g 


g 


g
4
8
16
fifth
sixth
x
x
x
half  life
half  life
g 


g 


g
16
32
64
Therefore, 1/64 of the initial radioactivity will remain in the year 2010. Converting to %,
1/64 x 102 = 1.6%
10.42
Fusion combines small nuclei to produce energy.
10.44
a.
The fusion process involves the building of larger nuclei by the combination of smaller
nuclei. This process produces both heat and light.
b.
As with fission, the heat generated by the fusion process could be used to generate steam.
The steam would be used to drive a turbine to create electricity.
10.46
Fission reactions produce waste products of radioactive isotopes with long half lives. This makes
disposal of the waste difficult and costly. Nuclear accidents could release contamination into the
environment which could, in turn, result in long term health hazards.
10.48
Advantages of breeder reactors include the ability to make their own fuel from abundant
uranium-238, and more cost effective operation than conventional nuclear power reactors.
Disadvantages of breeder reactors include the potential of environmental damage, and the
proliferation of the plutonium isotope used to build nuclear bombs.
10.50
Carbon rods absorb free neutrons as needed, thereby moderating the fission reaction.
10.52
Fusion
10.54
Carbon-12 is a stable isotope; its mass does not change with time. Carbon-14 is radioactive; its
mass decreases predictably with time. Hence, the changing mass ratio of carbon-12 and carbon14 can be used to indicate the approximate age of the object.
10.56
98
42 Mo
10.58
a.
Iodine-131 is used as a tracer to determine the rate of iodine uptake by the thyroid gland.
b.
Thallium-201 is used as a tracer in the diagnosis of coronary artery disease.
+
1
0n

99
42 Mo
10.60
Medically useful isotopes may be produced by bombardment with neutrons or protons.
Alternatively, a radioactive isotope may be a product of the radioactive decay of a substance that
has a longer half-life. (For example, Mo-99 decays to produce Tc-99m.)
10.62
a.
Concrete is both thicker and more dense than wood paneling. As such it is a better absorber
of radiation and would reduce the transmission of radiation through the walls.
b.
Lead is a very dense substance; it is a good absorber of radiation, including gamma
radiation. Hence, a lead-lined apron significantly increases the level of protection for the
person wearing the apron.
10.64
A major source of radiation is the sun; cosmic radiation. At high altitudes, the stratospheric
density is low. Hence, it is a less-efficient absorber of radiation than the atmosphere at the earth's
surface.
10.66
A Geiger counter gives an instantaneous response to radiation. A film badge gives a picture of
exposure over time. For this reason, a Geiger counter would be more appropriate for assessing
immediate danger.
10.68
The lethal dose of radiation, LD50, is the dose that would be fatal to 50% of the exposed
population within 30 days.
10.70
a.
The rad (radiation absorbed dosage) is the dosage of radiation able to transfer 2.4 x 10 -3
calories of energy to 1 kilogram of matter.
b.
The rem (roentgen equivalent for man) is the product of the RAD and RBE (the relative
biological effect).
1. In the general symbol cleus, which of the three letters Z
A X for a nu
represents the atomic number?
2. What is the mass number of an alpha particle?
3. What is the mass number of a beta particle?
4. Write the complete symbol for a beta particle, in the form Z
A X.
5. Which type of radiation emitted by radioactive nuclei is similar in
mass to a helium atom?
6. Which type of radiation emitted by radioactive nuclei is negatively
charged?
7. Which type of radiation emitted by radioactive nuclei is a form of
electromagnetic radiation?
8. Which type of radiation emitted by radioactive nuclei has no mass?
9. Which type of radiation emitted by radioactive nuclei is the most
penetrating?
10. Which type of radiation emitted by radioactive nuclei is the
slowest
moving and least penetrating?
11. What may happen to a molecule if it is hit by gamma radiation?
12. What product nucleus would result from the alpha decay of radium226?
13. The isotope Ra decays to Rn by emitting radiation. Name the 88
226
86
222
type of radiation.
14. The isotope Ni decays to Cu by emitting radiation. Name the 28
63
29
63
type of radiation.
15. The isotope Tc decays to Tc by emitting radiation. Name the 43
99m
43
99
type of radiation.
16. Give the complete nuclear symbol for the isotope formed when the
isotope N undergoe 7
16 s beta decay.
17. Give the complete nuclear symbol for X in the following equation
for
radioactive decay.
18. Give the complete nuclear symbol for X in the following equation
for
radioactive decay.
92 2
4 X + 238U He 
19. What term is used to describe a radioactive isotope which decays
by
emitting only a gamma ray?
20. What is meant by the "binding energy" of a nucleus?
Page 1
21. What fraction of the initial amount of a radioactive isotope still
remains after four half-lives?
22. The half-life of tritium is 12 years. How long does it take for 1 3
H
ej
16.0 ng of tritium to decay to the point where 2.0 ng remains?
23. In Einstein's equation, E = mc2, what do E, m and c represent?
24. What is the nuclear process that produces energy in commercial
nuclear
power plants?
25. What kind of reactor produces its own fuel in the process of
providing
electrical energy?
26. What is the identity of the radioactive isotope involved in
radiocarbon
dating?
27. In what important way do cancer cells differ from normal cells?
28. What term is used to describe radioactive substances which are
used as
probes to study internal organs?
29. In what part of the body does iodine tend to concentrate?
30. Name any two radioactive isotopes commonly used in nuclear
medicine.
31. What type of disease can be conveniently studied using xenon-133
as a
tracer?
32. What device uses magnetic and electric fields to create highenergy
charged particles?
33. What is the term that describes the amount of radiation
attributable to
our everyday surroundings?
34. What is a film badge?
35. Which radioactive element is found in some indoor air?
36. What term represents the dosage of toxic material needed to kill
50% of
the exposed population in 30 days?
37. Who discovered, in 1896, that uranium ore emits radiation?
A. Curie
B. Becquerel
C. Geiger
D. Rutherford
E. Roentgen
38. Which of the following isotopes has no neutrons?
A. H-1 B. H-2 C. H-3 D. He-4 E. C-12
39. Which nuclear particle is the same as an He2+ ion?
A. alpha B. beta C. gamma D. proton E. electron
Page 2
40. How many protons are contained in one alpha particle?
A. 0 B. 1 C. 2 D. 4 E. 6
41. How many neutrons are contained in an alpha particle?
A. 0 B. 1 C. 2 D. 4 E. 6
42. The symbol He represe nts 2
4
A. an alpha particle
B. a beta particle
C. a gamma ray
D. a positron
E. a deuteron
43. Which radioactive emission is stopped by a few sheets of paper?
A. alpha B. beta C. gamma D. proton E. electron
44. The symbol e represen ts -1
0
A. an alpha particle
B. a beta particle
C. a gamma ray
D. a positron
E. a deuteron
45. Which of the following particles or rays requires barriers of lead
and/or concrete for protection?
A. alpha B. beta C. gamma D. proton E. electron
46. What particle or nucleus X is needed to complete the following
equation:
86
210
84
206 + X? Rn Po 
A. proton
B. uranium-235
C. alpha
D. beta
E. gamma
47. What particle or nucleus X is needed to complete the following
equation:
19
40
-1
0 + X? K e 
A. hydrogen-3
B. carbon-14
C. argon-40
D. potassium-41
E. calcium-40
Page 3
48. When the isotope es alpha decay, the product isotope is 83
214Bi undergo
A.
212
81Tl B.
212
79 Au C.
214
84Po D.
210
81Tl E.
214m
83 Bi
49. When the isotope es beta decay, the product isotope is 83
214Bi undergo
A.
215
84Po B.
212
79 Au C.
214
84Po D.
210
81Tl E.
214m
83 Bi
50. What information is conveyed by the m in 99mTc?
A. The mass of the isotope is 99.
B. The isotope is metastable.
C. The isotope is man-made.
D. There are multiple isotopes for this element.
E. This is the most abundant isotope for this element.
51. How many half-lives are needed for a 400.0 ng sample of a
radioactive
isotope to decay to 12.5 ng?
A. 4 B. 5 C. 10 D. 16 E. 32
52. It has been stated that ten half-lives are sufficient for a
radioactive
isotope sample to decay to background levels. What fraction of the
initial amount of an isotope actually does remain after ten halflives?
A. 0.100
B. 0.0500
C. 0.0100
D. 9.77 10-4
E. 1.00 10-10
53. A 50. mg sample of iodine-131 was placed in a container 32.4 days
ago.
If its half-life is 8.1 days, how many milligrams of iodine-131 are
now
present?
A. 47.3 mg B. 3.1 mg C. 3.24 mg D. 0.81 mg E. 6.2 mg
54. What is the name of the nuclear process in which heavy nuclei
split
into two lighter nuclei?
A. gamma decay
B. beta decay
C. breeding
D. fission
E. fusion
Page 4
55. What is the process responsible for energy production in the sun?
A. chemical combustion
B. oxidation-reduction
C. decomposition
D. fission
E. fusion
56. What fissionable isotope or element is produced from U-238 in a
breeder
reactor?
A. U-235
B. U-238
C. Pu
D. He
E. H-3
57. From which of the following isotopes is carbon-14 formed by cosmic
ray
bombardment in the upper atmosphere?
A. Li-5
B. U-238
C. O-16
D. O-18
E. N-14
58. Which one of the following radioactive isotopes is used to
diagnose
coronary disease?
A. thallium-201
B. xenon-133
C. carbon-14
D. iodine-131
E. uranium-238
59. The isotope iodine-131 is used in studies of the
A. heart
B. lung
C. liver
D. thyroid
E. kidney
60. Magnetic resonance imaging (MRI) depends on the presence in tissue
of
A. carbon atoms
B. hydrogen atoms
C. water molecules
D. radioactive isotopes
E. magnetic particles
Page 5
61. Which of the following measures of radioactivity takes into
account the
relative biological effect (RBE) of the radiation involved?
A. rem
B. rad
C. roentgen
D. curie
E. half-life
62. T F The mass of an alpha particle is equal to that of four
protons.
63. T F Beta particles are a form of electromagnetic energy.
64. T F Gamma rays move at the speed of light.
65. T F Gamma rays are fast moving electrons.
66. T F A metastable isotope decays by emitting a gamma ray.
67. T F Compared to the energy of chemical bonds, nuclear binding
energy
is very weak.
68. T F Nuclei with 84 or more protons are radioactive.
69. T F Isotopes with even numbers of protons and neutrons are
generally
more stable than those with odd numbers of these particles.
70. T F A radioactive sample will decay completely in two half-lives.
71. T F After four half-lives, the fraction of a radioactive isotope
remaining is one eighth of the initial amount.
72. T F The sun's source of energy is nuclear fission.
73. T F Commercial nuclear power plants use the fusion process to
generate electrical energy.
74. T F When an atom is hit by gamma radiation, it may become ionized.
75. T F Doubling the distance from a source of radioactivity will
halve
the radiation intensity.
76. T F When the strength of a radioactive source is specified in
curies,
it provides no information on the biological effects of the
radiation.
77. T F The term LD50 means the dose of toxic material that will be
needed
to kill 50% of the exposed population within 30 days.
Page 6
Answer Key for Test "chapter10.tst", 8/17/04
No. in
Q-Bank
No. on
Test Correct Answer
10 1 1 Z
10 2 2 4
10 3 3 0
10 4 4
-1
0e
10
10
10
10
10
10
10
10
10
10
10
10
5 5 alpha particle
6 6 beta particle
7 7 gamma ray
8 8 gamma ray
9 9 gamma ray
10 10 alpha particle
11 11 loss of electrons, or ionization
12 12 radon-222
13 13 alpha particle
14 14 beta particle
15 15 gamma ray
16 16
8
16 O
10 17 17
6 7
14 + X 14 C N 
10 18 18
90
234Th
10 19 19
10 20 20
neutrons
10 21 21
10 22 22
metastable isotope
It is the energy responsible for holding the protons and
together in the nucleus.
one sixteenth (0.061)
36 years
10 23 23 E = energy; m = mass; c = speed of light
10 24 24 fission
10 25 25 breeder reactor
10 26 26 C-14 or carbon-14
10 27 27 They undergo much more rapid cell division.
10 28 28 tracers or radioactive tracers
10 29 29 thyroid gland
10 30 30 (from) iodine-131, technetium-99m, thallium-201, xenon-133,
barium-131, chromium-51
10 31 31 pulmonary disease
10 32 32 particle accelerator
10 33 33 background level of radiation
10 34 34 It is a badge worn by radiation workers, containing a film
which
measures their cumulative radiation dose.
10 35 35 radon
10 36 36 LD50
10 37 37 B
10 38 38 A
10 39 39 A
10 40 40 C
10 41 41 C
10 42 42 A
10 43 43 A
10 44 44 B
Page 1
Answer Key for Test "chapter10.tst", 8/17/04
No. in
Q-Bank
No. on
Test Correct Answer
10 45 45 C
10 46 46 C
10 47 47 E
10 48 48 D
10 49 49 C
10 50 50 B
10 51 51 B
10 52 52 D
10 53 53 B
10 54 54 D
10 55 55 E
10 56 56 C
10 57 57 E
10 58 58 A
10 59 59 D
10 60 60 B
10 61 61 A
10 62 62 F
10 63 63 F
10 64 64 T
10 65 65 F
10 66 66 T
10 67 67 F
10 68 68 T
10 69 69 T
10 70 70 F
10 71 71 F
10 72 72 F
10 73 73
10 74 74
10 75 75
10 76 76
10 77 77
Page 2
F
T
F
T
T