# Homework Help: Energy released in fusion

1. Oct 26, 2014

### desmond iking

1. The problem statement, all variables and given/known data
Two 2_1 H atoms undergo fusion to form 3_1 H and 1_1 H atom
calculate the energy released by 1.0kg of deuterium..
the amu is given as :2_1 H : 2.01402u
3_1 H : 3.016049u
1_1 H : 1.007825 u
P/s : i am sure that the energy produced is 3.89MeV ....

2. Relevant equations

3. The attempt at a solution
0.5 x (1000/2) x 6.02x10^23 x 3.89MeV = 5.85x10^26 MeV

Is my working correct?

2. Oct 26, 2014

### haruspex

Why both the 0.5 and the /2?
I get exactly double your answer by calculating the fraction of mass lost, then the total mass lost, then using E=mc2.

3. Oct 26, 2014

### desmond iking

0.5 means there' re 2 H atom /2 means mrr 2g... I am calculating the energy released for 1 H atom...

4. Oct 26, 2014

### desmond iking

So I divide 2

5. Oct 26, 2014

### haruspex

Yes, but why twice (0.5, then /2)?

6. Oct 26, 2014

### desmond iking

Mrr is 2g. And there re 2 H atom sow I divide 2 twice

7. Oct 26, 2014

### haruspex

Sorry, you've lost me. What are Mrr and 2g in this context?

8. Oct 27, 2014

### desmond iking

molar mass of deuterium= 2g

Last edited: Oct 27, 2014
9. Oct 27, 2014

### haruspex

Ah, OK. I didn't recognise it because you truncated it from the given 2.01402.
I've found the mistake in my own working and now get almost the same as you do: 5.80E26.