Energy released in nuclear reactions: total binding energy or per nucleon

[BomboshMan]

I'm doing AQA Physics A unit 5 next Monday, and I've been doing some past papers but I'm not sure about how to answer questions on the energy released in nuclear reactions. The mark schemes say that the energy released is equal to the change of binding energy per nucleon but I thought that the energy released is equal to the change of total binding energy, and it is this second one which is written in my textbook. Which one is right, and if it is the per nucleon one which is right, why?

Thankaa :D

 

[mfb]

The total energy released/required in nuclear reactions is the change of the total binding energy (assuming that the number of particles stays the same, e.g. no neutron decay involved).
The energy released per nucleon is the total energy divided by the number of nucleons and therefore related to the binding energy per nucleon.