Nuclear Applications Mass and Energy

[Mahan93]

I'm really struggling with the homework that was set for this, I can't even do question 1 never mind the rest of it, can anyone help at all? I have left all my notes in my folder in college which isnt helping the situation!

[jmorris]

Lets do question 1 first:
(i) You need to complete the equation. Remember in nuclear fission 3 neutrons are released. You then need to complete the nucleon number of Xe.
(ii) You know the nucleon number (number of protons plus neutrons in each of the nuclei U235, Sr98 and Xe should be 135 - so you can mark these on the graph.
(iii) From the graph you can find the binding energy per nucleon of each of the nuclei. To find binding energy of each multiply by nucleon number.
Work out binding energy for U, then work out binding energy for Sr and Xe, add them together and take away binding energy of U to find energy released. Graph is in MeV so answer will be.
Let me know how you go on

[jmorris]

Remember for a lot of the wordy questions, the definitions page will help and the powerpoint on nuclear reactors will also be helpful

[Mahan93]

Yh, I just did that and I got the right answer, thanks! it wasnt making any sense at all when i first read it but it seems i can do them now! Thank you

[jmorris]

Good

Any more problems, let me know

[matthewfrain]

I really don't understand Question 5 in this booklet. It's about labelling the graph etc...
Please would you be able to help? :') Thanks!

[jmorris]

Question 5 is about the N-Z graph band of stability. ( N is number of neutrons, Z is number of protons). You have to know the graph goes through N=10, Z=10 - up to his point it is a straight line and after this it curves upwards. A point to mark on the graph is N=120 when Z=80.
Unstable nuclei will be above or below this band of stability line. The unstable nuclei decay in an attempt to 'get closer' to the band of stability line. Alpha emitters are at values bigger than Z= 60, beta minus emitters are lower down than Z=60 and above the line and beta plus emitters are lower than Z=60 and below the line.
Have a look at the graph on page 172 of A2 book and prove to yourself that each of these types of emiision will move the nuclei closer to the band of stability.
Remember in beta plus emission a proton changes to a neutron (so Z goes down by 1 and N goes up by 1) and in beta minus emission a neutron changes to a proton (so Z goes up by 1 and N goes down by 1) In alpha emission both N and Z go down by 2 - so this is a quick way to reduce overall numbers of protons and neutrons - alpha emitters are too big to be stable.
See if you can now do the question - I will post some more help in the revision notes.
Let me know how you go on and if there is anything else you need help with.

[jmorris]

How is everyone getting on with these questions?

[Joseph Wardley]

1) Find the atomic mass
2) From then on i know i can find the nuclear mass by subtracting number of electrons x (.00055)
3) I then find mass of protons by doing number of protons x (1.00728)
4) I then find mass of protons by doing number of nutrons x (1.00867)
5) do (mass protons and nutrons)- Atomic mass. This is the mass defect.
6) to find bond energy you do (mass defect) x 931.5
7) to find bind energy per nucleon you do (bind energy)/ number of nucleons

I have been stuck on number one for a few days, done the rest of the homework but these questions and the past paper.

[jmorris]

Not sure what you are asking here Joe. Everything you have written seems fine. Which question are you stuck on?

Janet

[Sponsored content]