# Energy Change Nuclear Chemistry

1. Nov 19, 2016

### NY152

1. The problem statement, all variables and given/known data
Determine the energy change, delta E, in J when 500 g of 229/90 Th undergoes the following nuclear reaction:
229/90 Th --> 225/88 Ra + 4/2 He
The nuclear masses in amu or g/mol are: Th-229: 229.03175; Ra-225: 225.02360; He-4: 4.00260

2. Relevant equations
delta E = deltam(c)^2
c= 3*10^8
1 g= 6.02*10^23

3. The attempt at a solution
I know how to do a problem like this without a different mass input, but I have no idea how to incorporate the 500 grams into the solution. The answer is -1.09*10^12 J

2. Nov 19, 2016

### Bystander

Step at a time: how many mol?

3. Nov 19, 2016

### NY152

Would you do 500 g Th * 1 mol Th/229.03175 g Th = 2.183 mol Th

4. Nov 19, 2016

### Bystander

Yes. Can you take it the rest of the way?

5. Nov 19, 2016

### NY152

Well I don't really know what to do with that number now. How do I incorporate it into the change in mass?

6. Nov 19, 2016

### Bystander

229 = 225 + 4; what is the mass defect?

7. Nov 19, 2016

### NY152

The mass defect would be around -4, but so then how do you incorporate the 2.183 mol of Th??

8. Nov 19, 2016

### Bystander

"WORNG!" Try again, please.

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