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CHAPTER 19 BASIC HOMEWORK:

NUCLEAR CHEMISTRY I

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Question 1

  

Answer: Correct

 

    

    

 

Question 2

What is the mass number?

 

    

    

 

Question 3

What is the number of neutrons?

 

Explanation

Typically the number of neutrons is the same as the number of protons with the exception of isotopes.

But this is an isotope so take the mass number and subtract the protons from it.

67-30 = 37

 

Question 4

What is the number of electrons?

 

Explanation

Take the charge into account (2+)

So that means there are two less electrons than there should be so 30-2=28

 

Question 5

What is the atomic number?

 

Explanation

Atomic number is the same as the proton number

 

Question 6

Which of the following statements is INCORRECT regarding nuclear reactions?

Comparison of Chemical and Nuclear Reactions

Select one:
 Correct

 

    

    

 

Question 7


Select one:
 Correct

 

    

    

 

Question 8

Select one:
 Correct

 

    

    

 

Question 9

Select one:
 Correct

 

    

    

 

Question 10

The positively charged protons in the nucleus are held together by the strong force made possible by the presence of neutrons. Based on the graph in the supplement, which of the following statements are correct?

Select one or more:
 Correct
 Correct
 Correct

 

    

    

 

Question 11

Predict the mode of decay and the product for 32Si. (You need your periodic table for this and the following questions.)

Predicting Nuclear Reactions

Select one or more:
 Correct
 Correct

 

    

    

 

Question 12

Predict the mode of decay and the product for 227Ac.

Select one or more:
 Correct
 Correct

 

    

    

 

Question 13

Predict the mode of decay and the product for 22Na.

Select one or more:
 Correct
 Correct
 Correct

 

    

    

 

Question 14

To get to a stable nucleus, there may be a series of decays involving alpha and beta particles. How many alpha particles are emitted in the decay series that begins with 237Np and finally produces the stable isotope 209Bi?

Hint, take the time to write and balance the equation using Z and A.

 

Explanation

237Np   ------>   7 4He     +     209Bi            + 4 0

93                        2                   83                   -1

 

Question 15

How many beta particles are emitted?

 

    

    

 

Question 16

130I decays by emission of beta particles to form stable 130Xe. A 3.00 g iodine sample containing some I-130 was recorded as having 1829 disintegrations per min. k = 0.00094 min -1. How many radioactive I-130 atoms are present in the sample?

Nuclear Decay is First Order

Correct

 

Explanation

Hint, just use R = kN and solve for N.

1829 = 0.00094(N)

N=1945744.681

 

Question 17

The radioactive decay of a sample containing an unknown radioactive isotope produced 8898 disintegrations per minute. 10.17 days later, the rate of decay was found to be 2898 disintegrations per minute. Calculate the half-life in days for the unknown radioactive isotope.

Half Life Calculation

Correct

 

Explanation

ln (Rt/Ro) = -kt

R0=8898d/min * 1440 min/day = 12813120

Rt= 2898*1140=3303720

ln (3303720/12813120) = -k(10.17)

k=0.110

t1/2 = 0.693/k = 6.28

 

Question 18

A certain radioactive element has a half life of 7403 years. How much of a 7.76 g sample is left after 8663 years?
Correct

 

Explanation

Your content goes here...

 

Question 19

The half-life of carbon-14 is 5,730 years. An artifact produces 13.9 disintegrations of 14C per minute per gram of carbon in the sample. Estimate the age of this sample assuming that its original radioactivity was 15.3 disintegrations per minute per gram of carbon.

Half Life Calculation 3

Correct

 

Explanation

t1/2 = 0.693/k=5730

k=0.0001209

ln(13.9/15.3)= -0.0001209t

t=793.468

 

Question 20

What is the energy released when 0.771 g are converted to energy? Express your answer in joules. For self-consistent units you must use kg because 1 J = 1 kg m2/s2.

Mass and Energy

Correct

 

Explanation

E=mc^2

=0.771(3e8)^2

=6.939e16

 

Question 21

What is the mass defect of 27Al in u? The mass of 1 atom of Al-27 is 26.9815 u.

Mass Defect

Correct

 

Explanation

# of neutrons =14

# of protons =13

14*1.008665 - 14.12

13*1.007825=13.10

13.10+14.12=27.2333

mass defect = 27.223 - 26.9815

=0.2415

 

Question 22

What is the nuclear binding energy per mole if the mass defect of a certain isotope is 0.0800 u per atom or 0.0800 g per mol? Express your answer in joules. Remember to use self-consistent units.

Nuclear Binding Energy

Correct

 

Explanation

E=mc^2

=(0.0800g/mol * 1kg/1000g) * (3e8)^2=7.2e12


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