23 Nuclear Chemistry.ppt-b

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Nuclear Chemistry
Chapter 23
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• In chemical reactions, only the outer electrons of
the atoms are disturbed.
• In nuclear reactions, the nuclear changes that
occur are independent of the chemical
environment of the atom.
20 | 2
Radioactive decay is the process in which
a nucleus spontaneously disintegrates,
giving off radiation.
A nuclear bombardment reaction is a
nuclear reaction in which a nucleus is
bombarded, or struck, by another nucleus or
by a nuclear particle.
20 | 3
We write nuclear equations using nuclide
symbols. Nuclear equations are balanced
when the total mass number and the atomic
number on both reactant and product sides
are equal.
• Let’s look at the decay of uranium-238.
20 | 4
Symbols for other particles are given below:
Proton
1
1
H or 11P
Neutron
1
0
Electron
0
-1
Positron
0
1
Gamma photon
0
0
n
e or -01β
e or 01β
20 | 5
γ
Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Mass Number
Atomic Number
A
ZX
Element Symbol
proton
1p
1H
or
1
1
neutron
1n
0
electron
0b
0e
or
-1
-1
positron
0b
0e
or
+1
+1
a particle
4He
4a
or
2
2
A
1
1
0
0
4
Z
1
0
-1
+1
2
23.1
Balancing Nuclear Equations
1. Conserve mass number (A).
The sum of protons plus neutrons in the products must equal
the sum of protons plus neutrons in the reactants.
235
92 U
+ 10n
138
55 Cs
+
96
37 Rb
+ 2 10n
235 + 1 = 138 + 96 + 2x1
2. Conserve atomic number (Z) or nuclear charge.
The sum of nuclear charges in the products must equal the
sum of nuclear charges in the reactants.
235
92 U
+ 10n
138
55 Cs
+
96
37 Rb
92 + 0 = 55 + 37 + 2x0
+ 2 10n
23.1
212Po
decays by alpha emission. Write the balanced
nuclear equation for the decay of 212Po.
4
alpha particle - 42He or 2a
212Po
84
4He
2
+ AZX
212 = 4 + A
A = 208
84 = 2 + Z
Z = 82
212Po
84
4He
2
+ 208
82Pb
23.1
Radon-222 is a radioactive noble gas that
is sometimes present as an air pollutant
in homes built over soil with high
uranium content (uranium-238 decays to
radium-226, which in turn decays to
radon-222). A radon-222 nucleus decays
to polonium-218 by emitting an alpha
particle. Write the nuclear equation for
this decay process.
20 | 9
From the periodic table, we can see that the atomic
number of radon is 86 and the atomic number of
polonium is 84. For the alpha particle symbol, both
He and a are correct.
222
86
222
86
Rn  42 α 
Rn  42 He 
218
84
Po
218
84
Po
To check, total the mass numbers and atomic
numbers on each side of the reaction.
Mass numbers:
222 = 4 + 218
Atomic numbers:
86 = 2 + 84
20 | 10
Iodine-131 is used in the diagnosis and
treatment of thyroid cancer. This isotope
decays by beta emission. What is the
product nucleus?
20 | 11
From the periodic table, we find that the atomic
number of iodine is 53. The beta particle symbol is
correct as either e or b.
131
0
A
I

e

53
-1
ZX
131
53
I  -01β  AZ X
Now find the atomic and mass number of the
product:
131 = 0 + A
53 = –1 + Z
A = 131
Z = 54
Next, use the atomic number to find the symbol: Xe.
131
53
I  -01e 
131
54
131
53
Xe
20 | 12
I  -01β 
131
54
Xe
23.1
n/p too large
beta decay
X
Y
n/p too small
positron decay or electron capture
23.2
Nuclear Stability
It is reasonable to wonder how a nucleus
with positively charged protons is held
together, given that positively charged
particles repel each other.
The stability of the nucleus is due to the
strong nuclear force. The nuclear force acts
only at very short distances, about 10-13 m.
At this distance it is stronger than the
electric repulsion.
20 | 15
The shell model of the nucleus is a nuclear
model in which protons and neutrons exist
in levels, or shells, analogous to the shell
structure that exists for electrons.
20 | 16
Just as certain very stable numbers of
electrons (2, 10, 28, and so on) occur when
a shell is filled, so there are magic numbers
for nucleons.
A magic number is the number of nuclear
particles in a completed shell of protons and
neutrons.
For protons, the magic numbers are 2, 8, 20,
28, 50, and 82. For neutrons, the magic
numbers also include 114.
20 | 17
•
20 | 18
For stable nuclides with Z ≤ 20, the ratio of
neutrons to protons is between 1 and 1.1.
For stable nuclides with Z > 20, the ratio of
neutrons to protons increases to about 1.5.
This is believed to be due to the increasing
repulsion between protons, which requires
more neutrons to increase the strong nuclear
force.
No stable nuclide exists for Z > 83, perhaps
because the proton repulsion becomes too
great.
20 | 19
Nuclear Stability
•
Certain numbers of neutrons and protons are extra stable
•
n or p = 2, 8, 20, 50, 82 and 126
•
Like extra stable numbers of electrons in noble gases
(e- = 2, 10, 18, 36, 54 and 86)
•
Nuclei with even numbers of both protons and neutrons
are more stable than those with odd numbers of neutron
and protons
•
All isotopes of the elements with atomic numbers higher
than 83 are radioactive
•
All isotopes of Tc and Pm are radioactive
23.2
• Predict which nucleus in each pair should
be more stable and explain why.
• a. astatine-210 and lead-207
b. molybdenum-91 and molybdenum-92
c. calcium-37 and calcium-42
20 | 21
a. Astatine-210 has 85 protons and 125 neutrons.
Lead-207 has 82 protons and 125 neutrons.
Lead-207 is more stable because it has a
magic number of protons. Also, At has > 83
protons.
b. Molybdenum-91 has 42 protons and 49
neutrons.
Molybdenum-92 has 42 protons and 50
neutrons.
Molybdenum-92 is more stable because it has
a magic number of neutrons.
20 | 22
c. Calcium-37 has 20 protons and 17
neutrons.
Calcium-42 has 20 protons and 22
neutrons.
Calcium-42 is more stable because it has
an even number of neutrons. (Both have a
magic number of protons.)
20 | 23
• There are six common types of radioactive
decay.
1. Alpha emission
Emission of an alpha particle from an unstable
nucleus.
20 | 24
2. Beta emission
Emission of a beta particle from an unstable
nucleus. Beta emission is equivalent to a
neutron converting to a proton.
20 | 25
3. Positron emission
Emission of a positron particle from an
unstable nucleus. Positron emission is
equivalent to a proton converting to a neutron.
20 | 26
4. Electron capture
The decay of an unstable nucleus by capture
of an electron from an inner orbital of the
atom. Electron capture is equivalent to a
proton converting to a neutron.
20 | 27
5. Gamma emission
Emission from an excited nucleus of a gamma
photon, corresponding to radiation with a
wavelength of approximately 10-12 m.
Technetium-99m is an example of a
metastable nucleus; it is in an excited state
and has a lifetime of ≥ 10-9 s.
Copyright © C
20 | 28
6. Spontaneous fission
The spontaneous decay of an unstable
nucleus in which a heavy nucleus of mass
number greater than 89 splits into lighter
nuclei and energy is released.
20 | 29
Nuclides to the left of the band of stability
have a neutron-to-proton ratio, N/Z, that is
too large. They decay by beta emission,
which reduces the N/Z ratio by converting a
neutron to a proton.
Nuclides to the right of the band of stability
have an N/Z ratio that is too small. These
nuclides decay by either positron emission
or electron capture. Either process increases
the N/Z ratio by converting a proton to a
neutron.
20 | 30
•
20 | 31
Thallium-201 is a radioactive isotope used
in the diagnosis of circulatory impairment
and heart disease. How do you expect it to
decay?
Thallium-201 has 81 protons and 120 neutrons.
N/Z < 1.5 (too small).
Thallium-201 will decay by either electron capture or
positron emission—probably electron capture, given
that it is a heavy element.
20 | 32
Radioactive Decay Series
A sequence in which one radioactive
nucleus decays to a second, which then
decays to a third, and so forth, until a stable
nucleus of lead is formed.
Three radioactive decay series are found
naturally: uranium-238, uranium-235, and
thorium-232.
20 | 33
The radioactive decay series
for uranium-238 ends with
lead-206
Copyright © Cengage
Learning. All rights res
20 | 34
You have two samples of water, each made
up of different isotopes of hydrogen: one
contains hydrogen-1 and the other
contains hydrogen-3.
a. Would you expect these two water
samples to be chemically similar?
b. Would you expect these two water
samples to be physically the same?
c. Which one of these water samples would
you expect to be radioactive?
20 | 35
a. Yes, isotopes have similar chemical
properties.
b. No, the hydrogen-3 water has more mass
than the hydrogen-1 water.
c. The hydrogen-3 (tritium) water should be
radioactive.
20 | 36
Nuclear Bombardment Reactions
Nuclear bombardment reactions are not
spontaneous. They involve the collision of a
nucleus with another particle.
Transmutation is the change of one
element into another by bombarding the
nucleus of the element with nuclear
particles or nuclei.
20 | 37
When Rutherford allowed alpha particles to
collide with nitrogen nuclei, he found that a
proton was ejected and oxygen was formed.
20 | 38
James Chadwick proposed the existence of the
neutron based on the result of bombarding
beryllium-9 with alpha particles. The product
included neutral radiation we now know as
neutrons. 9 Be  4 He  12C  1 n
4
2
6
0
The first radioactive nucleus produced in the
laboratory was phosphorus-30.
27
13
Al  2 He  15P  0n
4
30
1
Phosphorus-30 decays by positron emission.
30
15
P  Si  e
30
14
20 | 39
0
1
In the abbreviated notation for nuclear
bombardment reactions, the starting nucleus
is written first. It is followed by, within
parentheses, the bombarding particle, a
comma, and then the ejected particle.
Finally, the product nucleus is written.
20 | 40
For example, for the bombardment of nitrogen14 with an alpha particle, which leads to the
ejection of a proton, the reaction is written as
follows:
4
17
1
N

He

O

H
7
2
8
1
14
The abbreviated notation is
14
7

4
2
1
1

17
N He, p 8 O
20 | 41
The following symbols are used for nuclide
particles when writing them using the
abbreviated notation for a nuclear
bombardment reaction.
Neutron, n
Proton, p
Deuteron (hydrogen-2), d
Alpha (helium-4), a
20 | 42
Sodium-22 is made by the bombardment
of magnesium-24 (the most abundant
isotope of magnesium) with deuterons. An
alpha particle is the other product. Write
the abbreviated notation for the nuclear
reaction.
Reaction :
24
12
Mg  H 
2
1
Abbreviate d notation :
20 | 43
24
12
Na  He
22
11
4
2
22


Mg d, a 11Na
A neutron is produced when lithium-7 is
bombarded with a proton. What product
nucleus is obtained in this reaction?
Reaction : 73 Li  11H  74 Be  01n
The product is 74 Be.
20 | 44
Energy of Nuclear Reactions
Nuclear reactions involve changes of
energy on a much larger scale than occur in
chemical reactions. This energy is used in
nuclear power reactors and to provide the
energy for nuclear weapons.
20 | 45
Mass–Energy Calculations
When nuclei decay, they form products of
lower energy. The change of energy is
related to changes of mass, according to the
equation derived by Einstein, E = mc2.
20 | 46
 DE = (Dm)c2
We can compute the change in energy for a
nuclear reaction by calculating the change
in mass. The change in mass must be given
in kilograms to satisfy Einstein’s equation.
The masses of some elements and other
particles are given in Table 20.3.
20 | 47
Consider the following nuclear reaction, in
which a lithium-7 nucleus is bombarded with a
hydrogen nucleus to produce two alpha
particles:
7
1
4
Li

H

2
3
1
2 He
What is the energy change of this reaction
per gram of lithium?
Nuclear masses:
7
3 Li, 7.01436 amu
1
1
H, 1.00728 amu
4
2
He, 4.00150 amu
20 | 48
• First we find the change in mass for one mole of
lithium-7.
• Mass of products:
• 2(4.00150 × 10-3 kg) = 8.00300 × 10-3 kg
• Mass of reactants:
• 7.01436 × 10-3 kg + 1.00728 × 10-3 kg
•
= 8.02164 × 10-3 kg
 Dm = –1.864 × 10-5 kg
20 | 49
 DE = (–1.864 × 10-5 kg)(2.998 × 108 m/s)2
 DE = –1.675 × 1012 J
ΔE
– 1.675  1012 J

7
g 3 Li 7.01436 g 73 Li
ΔE
11
7

–
2.388

10
J/g
3 Li
7
g 3 Li
20 | 50
Nuclear binding energy (BE) is the energy required to break
up a nucleus into its component protons and neutrons.
BE + 199F
911p + 1010n
E = mc2
BE = 9 x (p mass) + 10 x (n mass) – 19F mass
BE (amu) = 9 x 1.007825 + 10 x 1.008665 – 18.9984
BE = 0.1587 amu
1 amu = 1.49 x 10-10 J
BE = 2.37 x 10-11J
binding energy
binding energy per nucleon =
number of nucleons
2.37 x 10-11 J
= 1.25 x 10-12 J
=
19 nucleons
23.2
Nuclear binding energy per nucleon vs Mass number
nuclear binding energy
nucleon
nuclear stability
23.2
Nuclear Binding Energy
• The equivalence of mass and energy explains the
mass defect—that is, the difference between the
total mass of the nucleons that make up an atom
and the mass of the atom. The difference in mass
is the energy holding the nucleus together.
• The binding energy of a nucleus is the energy
needed to break a nucleus into its individual
protons and neutrons.
20 | 53
Both the binding energy and the mass
defect are indications of the stability of the
nucleus.
20 | 54
Rate of Radioactive Decay
The rate of radioactive decay is the number of nuclei
disintegrating per unit time. It is proportional to
the number of nuclei in the sample.
Rate = kNt
Nt = the number of radioactive nuclei at time, t.
k = the radioactive decay constant or rate constant
for radioactive decay; it is characteristic of the
nuclide.
20 | 55
The thorium-234 isotope decays by
emitting a beta particle. A 50.0-mg
sample of thorium-234 has an activity of
1.16 Ci. What is the decay constant for
thorium-234?
20 | 56
• First, we find the number of nuclei of thorium-234.
23
1
mol
6.022

10
nuclei
-6
Nt  50.0  10 g 

232.04 g
1mol
Nt  1.298  10 nuclei
17
Next, we convert the activity from curies to
disintegrations per second.
disintegra tions
3.700 x 10
s
Rate  1.16 Ci 
1 Ci
10 disintegra tions
Rate  4.292  10
s
10
20 | 57
Finally, we use the rate equation, understanding
that 1 disintegration = 1 nuclei.
rate
k
Nt
disintegra tions
4.292  10
s
k
1.298  1017 nuclei
10
k  3.31  10 -7 /s
20 | 58
• Half-life is the time it takes for one-half of
the nuclei in a sample to decay.
• Half-life is related to the decay constant by
the following equation:
t1
2
0.693

k
20 | 59
• After one half-life, half of the sample (0.5) remains.
• After two half-lives, one-fourth of the sample (0.25) remains.
• After three half-lives, one-eighth of the sample remains.
• This relationship is summarized in the following equation and
in the graph on the next slide.
n
 1
Fraction remaining    ,
2
where n  number of half - lives
20 | 60
•
20 | 61
Thallium-201 is used in the diagnosis of
heart disease. This isotope decays by
electron capture; the decay constant is
2.63 × 10-6/s. What is the half-life of
thallium-201 in days?
20 | 62
t1
2
0.693
t1 
2
k
0.693
t1 
-6
2
2.63  10
s
1 min
1h
1 day
5
 2.63  10 s 


60 s 60 min 24 h
t 1  3.05 days
2
Iodine-131 is used in the diagnosis and
treatment of thyroid disorders. The halflife for the beta decay of iodine-131 is
8.07 days.
a. What is the decay constant (in units
per second)?
b. What is the activity (in curies) of a
1.0-mg sample of iodine?
20 | 64
a. k  0.693
t1
2
0.693
k
24 h 60 min 60 s
8.07 days 


1 day
1h
1min
k  9.94  10 -7 /s
20 | 65
23
1
mol
6.022

10
nuclei
-6
Nt  1.0  10 g 
b. 
126.90 g
1mol
Nt  4.745  1015 nuclei
Rate  kNt
9.94  10-7
15
Rate 
 4.745  10 nuclei
s
9 nuclei
Rate  4.72  10
s
20 | 66
The rate constant is related to the fraction of
nuclei remaining by the following equation:
 Nt 
  - kt
ln
 N0 
N0 is the original number of nuclei.
Nt is the number of nuclei at time t.
Nt
is the fraction of nuclei remaining at time t.
N0
Nt  4.745 x 10 nuclei
15
20 | 67
A 0.500-g sample of iodine-131 is
obtained by a hospital. How much will
remain after a period of one week? The
half-life of this isotope is 8.07 days.
20 | 68
First, we find the value of k.
0.693
k
t1
2
0.693
k
1 week
8.07 days 
7 day
0.601
k
week
20 | 69
Next, we find the fraction of nuclei remaining.
 Nt 
  - kt
ln
 N0 
 Nt 
0.601
ln     1 week
week
 N0 
 Nt 
ln   - 0.601
 N0 
 Nt 

  0.548
 N0 
54.8% of nuclei remain.
20 | 70
Radioactive Dating
Because the rate of radioactive decay is constant,
this rate can serve as a sort of clock for dating
objects.
Carbon-14 is part of all living material. While a
plant or animal is living, the fraction of carbon-14
in it remains constant due to exchange with the
atmosphere. Once dead, the fraction of carbon-14
and, therefore, the rate of decay decrease. In this
way, the fraction of carbon-14 present in the
remains becomes a clock measuring the time since
the plant’s or animal’s death.
20 | 71
The half-life of carbon-14 is 5730 years.
Living organisms have a carbon-14 decay
rate of 15.3 disintegrations per minute per
gram of total carbon.
The ratio of disintegrations at time t to time
0 is equal to the ratio of nuclei at time t to
time 0.
20 | 72
A sample of wheat recovered from a
cave was analyzed and gave 12.8
disintegrations of carbon-14 per minute
per gram of carbon. What is the age of
the grain?
Carbon from living material decays at a
rate of 15.3 disintegrations per minute
per gram of carbon. The half-life of
carbon-14 is 5730 years.
20 | 73
Ratet = 12.8 disintegrations/min/g
Rate0 = 15.3 disintegrations/min/g
t1/2 = 5730 y
 Nt  rate t 12.8 disintegra tions/min/ g
  

 0.8366
 N0  rate 0 15.3 disintegra tions/min/ g
 Nt 
 Nt 

ln 
ln  
N0 
N0 
ln 0.8366 




t
 0.693 
 0.693 
t1

  

2
 k 
 5730 y 
3
t  1.48  10 y
20 | 74
Kinetics of Radioactive Decay
N
daughter
DN
rate = Dt
rate = lN
DN
= lN
Dt
N = N0exp(-lt)
lnN = lnN0 - lt
N = the number of atoms at time t
N0 = the number of atoms at time t = 0
l is the decay constant
ln2
l =
t½
23.3
Kinetics of Radioactive Decay
ln[N] = ln[N]0 - lt
ln [N]
[N]
[N] = [N]0exp(-lt)
23.3
Radiocarbon Dating
14N
7
+ 01n
14C
6
14C
6
14N
7
+ 11H
+ -10b + n
t½ = 5730 years
Uranium-238 Dating
238U
92
206Pb
82
+ 8 24a + 6-10b
t½ = 4.51 x 109 years
23.3
Nuclear Transmutation
14N
7
27Al
13
14N
7
+ 24a
+ 24a
+ 11p
17O
8
+ 11p
30P
15
+ 01n
11C
6
+ 42a
Cyclotron Particle Accelerator
23.4
Nuclear Transmutation
23.4
Nuclear Fission
235U
92
+ 01n
90Sr
38
1n + Energy
+ 143
Xe
+
3
0
54
Energy = [mass 235U + mass n – (mass 90Sr + mass 143Xe + 3 x mass n )] x c2
Energy = 3.3 x 10-11J per 235U
= 2.0 x 1013 J per mole 235U
Combustion of 1 ton of coal = 5 x 107 J
23.5
Nuclear Fission
Representative fission reaction
235U
92
+ 01n
90Sr
38
1n + Energy
+ 143
Xe
+
3
0
54
23.5
Nuclear Fission
Nuclear chain reaction is a self-sustaining sequence of
nuclear fission reactions.
The minimum mass of fissionable material required to
generate a self-sustaining nuclear chain reaction is the
critical mass.
Non-critical
Critical
23.5
Schematic Diagram of a Nuclear Reactor
23.5
Nuclear Fission
Annual Waste Production
35,000 tons SO2
4.5 x 106 tons CO2
3.5 x 106
ft3 ash
1,000 MW coal-fired
power plant
70 ft3
vitrified
waste
1,000 MW nuclear
power plant
23.5
Nuclear Fission
Hazards of the
radioactivities in spent
fuel compared to
uranium ore
From “Science, Society and America’s Nuclear Waste,” DOE/RW-0361 TG
23.5
Chemistry In Action: Nature’s Own Fission Reactor
Natural Uranium
0.7202 % U-235 99.2798% U-238
Measured at Oklo
0.7171 % U-235
Nuclear Fusion
Fusion Reaction
2
2
3
1
1 H + 1H
1 H + 1H
2H
1
+ 13H
6Li
3
+ 12H
4He
2
2
+ 10n
4He
2
Energy Released
6.3 x 10-13 J
2.8 x 10-12 J
3.6 x 10-12 J
Tokamak magnetic
plasma
confinement
23.6
Radioisotopes in Medicine
•
1 out of every 3 hospital patients will undergo a nuclear
medicine procedure
•
24Na,
•
131I,
t½ = 14.8 hr, b emitter, thyroid gland activity
•
123I,
t½ = 13.3 hr, gray emitter, brain imaging
•
18F,
t½ = 1.8 hr, b emitter, positron emission tomography
•
99mTc,
t½ = 14.8 hr, b emitter, blood-flow tracer
t½ = 6 hr, gray emitter, imaging agent
Brain images
with 123I-labeled
compound
23.7
Radioisotopes in Medicine
Research production of 99Mo
98Mo
42
+ 10n
99Mo
42
Commercial production of 99Mo
235U
92
99Mo
42
99mTc
43
+ 10n
99Mo
42
99mTc
43
99Tc
43
+ other fission products
+ -10b + n
+ g-ray
Bone Scan with
99mTc
t½ = 66 hours
t½ = 6 hours
23.7
Radiation Counters
There are two types of devices: ionization
counters and scintillation counters.
20 | 90
The Geiger counter is an ionization counter used to
count particles emitted by radioactive nuclei. It
consists of a metal tube filled with gas, such as argon.
20 | 91
A scintillation counter detects nuclear radiation
based on flashes of light generated in a material by
the radiation. A phosphor is a substance that emits
flashes of light when struck by radiation. In the
scintillation counter, the flashes of light are
detected by a photomultiplier tube.
20 | 92
• The activity of a radioactive source is the
number of nuclear disintegrations per unit
time occurring in a radioactive material.
• The curie (Ci) is a unit of activity equal to
3.700 × 1010 disintegrations per second.
20 | 93
Biological Effects and Radiation Dosage
The rad (from radiation affected dose) is
the dosage of radiation that deposits 1 × 10-2
J of energy per kilogram of tissue.
20 | 94
The rem is a unit of radiation dosage that is used
to relate various kinds of radiation in terms of
biological destruction. It equals the rad times a
factor for the type of radiation, called the relative
biological effectiveness (RBE).
• rem = rad × RBE
Beta and gamma radiation have an RBE of about
1, neutron radiation has an RBE of about 5, and
alpha radiation has an RBE of about 10.
20 | 95
The effect of radiation on a person depends on the
dosage and the length of time of the exposure. A
series of small doses have less overall effect than a
large dose given all at once.
A single dose of 500 rems is fatal to most people.
Detectable effects are seen at dosages as low as 30
rems. Background radiation averages about 0.1
rem per year but varies dramatically by location.
20 | 96
If you are internally exposed to 10 rads of a,
b, and g radiation, which form of radiation
will cause the greatest damage?
The a radiation has the highest RBE, so it will
cause the greatest damage.
20 | 97
Biological Effects of Radiation
Radiation absorbed dose (rad)
1 rad = 1 x 10-5 J/g of material
Roentgen equivalent for man (rem)
1 rem = 1 rad x Q
Quality Factor
g-ray = 1
b=1
a = 20
23.8
Chemistry In Action: Food Irradiation
Dosage
Effect
Up to 100 kilorad
Inhibits sprouting of potatoes, onions, garlics.
Inactivates trichinae in pork. Kills or prevents insects
from reproducing in grains, fruits, and vegetables.
100 – 1000 kilorads
Delays spoilage of meat poultry and fish. Reduces
salmonella. Extends shelf life of some fruit.
1000 to 10,000 kilorads
Sterilizes meat, poultry and fish. Kills insects and
microorganisms in spices and seasoning.
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