# Homework Help: Nuclear Reaction Problem!

1. Oct 8, 2011

### xpsellia

1. It has been found by experiment that the molar mass of the Rn nucleotide is 221.9703 g and that of the Po nucleotide is 217.9630 g. The molar mass of helium is 4.00150 g. Given this information, and the information from the class, calculate the energy evolved, in kJ, for the following nuclear reaction of 400.0 g of radon-222.

2. ΔE = Δmc^2 where c is speed of light

# of mol (n) = mass/molar mass

3. The attempt at a solution
Δm = 221.9703 - (217.9630 + 4.00150)
= 5.8 x 10^-3

ΔE = 5.8 x 10^-3 (3.0 x 10^8)
= 1740000 J

n = 400.0/ 221.9703
= 1.803 mol

How do I get the energy to be kJ/mol? My teacher said the answer should be ---- x 10^8 kJ.

2. Oct 8, 2011

### Staff: Mentor

Check your math - you are off by c.

3. Oct 9, 2011

### xpsellia

Oh yes sorry! I forgot to square c!

But then I ended up getting:
ΔE= 5.22 x 10^14

What do I do now with ΔE and the number of moles of radon to figure out the energy per mole in kJ?

4. Oct 10, 2011

### Staff: Mentor

If two apples cost \$4, what is a price in dollars per apple?

5. Oct 10, 2011

### phyzguy

Also, what is a Joule? Check your units.