Calculating Energy from Nuclear Reactions: A Step-by-Step Guide

[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

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.

 

[Borek]

Check your math - you are off by c.

 

[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?

 

[Borek]

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

 

[phyzguy]

Also, what is a Joule? Check your units.