Cobalt-60 is a radioactive isotope that is commonly used for cancer radiation th
ID: 511442 • Letter: C
Question
Cobalt-60 is a radioactive isotope that is commonly used for cancer radiation therapy. The cobalt-60 atom decays to the stable nickel-60 atom, releasing a beta particle (electron) and energy in the form of gamma rays:
60Co60Ni++
If you captured the energy from the decay of a 1.19 g pellet of isotopically pure cobalt-60, how long could you run a 80.0 W light bulb?
The relevant masses are as follows:
Gamma rays are massless.
Express your answer to three significant figures and include the appropriate units.
Substance Mass(g/mol) 60 Co 59.933819 60 Bi 59.930788 0.000549
Explanation / Answer
Lets see
The mass of Nickel-60+mass of electron = 59.930788 + 0.000549 = 59.931337 g/mol
Now
Mass lossed when Co-60 converts to Ni-60
59.933819 - (59.930788 + 0.000549) = 0.002482 g = 0.002482 x 10-3 Kg
Now we know that
E =mc2
= 0.002482 x 10-3 Kg x (3 x 108 m/s)2 = 2.2338 x 1011 J
But we have only 1.19 g of Co-60 , then
E = 2.2338 x 1011 J x (1.19/59.933819)
= 4.43526 x 109 J
Now
A Joule is a watt-second , Now we can find how many seconds we can power that 80.0 W light bulb
Then
4.43526 x 109 Watt.second / 80.0 Watt = 5.54 x 107 seconds
1 hour = 3600 seconds
so
5.54 x 107 seconds / 3600 s/Hr = 1.54 x 104 Hrs