Solutions to Radioactivity

 

1.       a)      alpha

          b)      positron

         

2.       a)     

          b)     

 

3.       a)      15N + 1H à 4He + 12 C; check that atomic numbers balance: 7 + 1 = 2 + 6

          b)      12C + 1H à 13N + g

                   13C + 1H à 14N + g      

 

4.       a)      fission; we are getting smaller nuclei

          b)      fusion; we are getting a bigger hydrogen nucleus

 

5.    a)   

 

       b)  

 

       c)   

 

       d)  

 

6. Compared to chemical changes, nuclear reactions release a lot more energy; they involve changes in the nucleus; they don't always preserve protons or neutrons; they don't conserve mass; and with the exception of X-rays, their electrons and shells don't change.

 

7.       We had shown on page 68 that for every mole of 2H fused, 1.65 X 109 kJ were released. (This was done by simply by

 

(1)Multiplying the mass lost per 2H atom by Avogadro’s number = mass lost per reacting mole

(2)Converting to kg

(3)Using E = mc2, and converting J to kJ

 

Now we’ll use that answer to get the energy released for 28 g.

 

28g of 2H / 2 g/mole = 14 moles 2H

 

14 moles 2H (1.65 X 109 kJ/mole) = 2.31 X 1010 kJ