# Binding Energy Concepts

1. Aug 11, 2007

### BMWPower06

1. The problem statement, all variables and given/known data
Consider the fission reaction in which 236U92 breaks up into 141Ba56 and 3 neutrons and an unknown fragment. Which of the following statements are true about this fission reaction in particular and nuclear reaction energies in general? You are given a plot of the binding energy (BE) per nucleon to help you.
http://aycu17.webshots.com/image/25736/2004649007142429776_rs.jpg

True False the unknown fission fragment will have Z = 33
True False the unknown fission fragment will have A = 95
True False a heavy nucleus (like uranium) can become more stable via a reaction that moves it back to the left on the BE curve
True False a heavy nucleus (like uranium) releases less energy in a single fission reaction than in one alpha decay
True False the fission products (two fragments plus 3 neutrons) have less total mass than the original 236U

3. The attempt at a solution

1. Z= Atomic Mass so true; must be equal before and after the equation
2. A= Atomic # so true; must be equal before and after the equation
5. The total mass must be equal before and after the reaction

My answers are in bold, and above are my reasons, i cant figure out what im doing wrong. Can anyone help?

Thanks

2. Aug 12, 2007

### BMWPower06

bump, any1 know?

3. Aug 12, 2007

### learningphysics

I think you have one and two right. I think 3 is True because higher binding energy -> more stability...

But 5 is true... right side has lower mass because energy has been released...

4. Aug 12, 2007

### BMWPower06

Turns out 1 and 2 are false?? Any1 have any clue why? that makes no sense

5. Aug 12, 2007

### learningphysics

Oops... sorry A = 92... 236-141-3... and Z = 36 (92-56)

A is the total number of protons+neutrons.
Z is the total number of protons.

I was mixing up number of protons and neutrons...

So yes, they're false.