1. Section Assessment Problems
Chapter 24
Nuclear Chemistry
Section Assessment Problems

2. Section 4.4
26. State what quantities are conserved when balancing a nuclear reaction.
Mass number and atomic number
29. Create a table showing how each type of radiation affects the atomic number and the mass number of an atom daughter nucleus
Particle
Atomic Number
Mass Number
α (42He) -2 -4
β (0-1e) +1
No change
γ (00γ)
Emitted
particle

3. Section 4.4 continued 105B → 63Li + 42He 13755Cs → 13756Ba + 0-1e
89. Boron-10 emits alpha particles and cesium-137 emits beta particles. Write balanced nuclear reactions for each radioactive decay.
105B → 63Li He
13755Cs → Ba e

4. Section 24.1
2. Compare the subatomic particles involved in nuclear and chemical reactions
Protons, electrons, and neutrons can be involved in nuclear change; only electrons are involved in chemical change.

5. Section 24.2 22688Ra → 42He + 22286Rn 10.0→5.00→2.50→1.25→ 0.625 g
15. Predict the nuclear equation for the alpha decay of radium- 226 used on the tips of older lightning rods
22688Ra → 42He Rn
16. Calculate how much of a 10.0 –g sample of americium-241 remains after four half-lives. Americium-241is a radioisotope commonly used in smoke detectors and has a half-life of 430 y
10.0→5.00→2.50→1.25→
0.625 g

6. Section 24.2
17. After 2.00 y, g of a radioisotope remains from a sample that had an original mass of g
A. Calculate the half-life N = N0(1/2)t/T
1.986 g = g x (1/2)(2.00 y)/T
1.986 g = (1/2)(2.00 y)/T = 0.5(2.00 y)/T
2.000 g
ln = ln (0.5(2.00 y)/T)
ln = ln (0.5) x (2.00 y)/T
T = ln (0.5) x (2.00 y) = 197 years ln

7. 17. After 2.00 y, g of a radioisotope remains from a sample that had an original mass of g B. How much of the radioisotope remains after y? N = g x (1/2)10.00 y/197 y = 1.93 g

8. Section 24.2 No Number of Half-lives Number Undecayed Nuclei 1 4 3 2
18. A sample of polonium originally has a mass of 1.0 g. Express the mass remaining as a percent of the original sample after a period of one, two, and three half-lives. Graph the percent remaining versus the number of half-lives.
Approximately how much time has elapsed when 20% of the original sample remains?
50%
25%
12.5%

9. Section 24.3
19. Write the balanced nuclear equation for the induced transmutation of aluminum-27 into sodium-24 by neutron bombardment. An alpha- particle is released in the reaction.
2713Al + 10n → 2411Na + 42He
20. Write the balanced nuclear equation for the alpha-particle bombardment of 23994Pu. One of the reaction products is a neutron.
23994Pu + 42He → 10n Cm