Maple TA 27-2

The question asks how much energy is lost per nucleon. Nucleon=proton+neutron.

energy = mass so you must find out how much mass is lost.

Add up all the masses of the proton, neutron, and electron. Subtract that from the actual mass (what is given). That is the mass lost to energy. This is in atomic mass units. You must convert to kg.

1 atomic mass unit = 1.66053886 × 10-27 kilograms

e=mc^2 <----- very important

note that this will be in joules. you need to convert this into Mev/nucleon. So you must convert to Mev and divide by number of nucleons.

1 MeV = 1.6x10-13 J

As mass is lost - energy is released so you should know the sign of the answer.

Need a tutor? email el@tantalizingstitches.com

This your question right?

You "throw together" 30 protons, 35 neutrons and 30 electrons forming a hypothetical atom with an atomic mass of 64.924767 u. What is the binding energy per nucleon in MeV (sheet 13,16) ? Indicate with a positive (negative) sign whether energy is released by (input into) the formation of the atom. (Atomic masses in u: proton 1.007276,neutron 1.008665,electron 0.000549 and neutral H atom 1.007825. Note that the atomic masses (like 64.924767 ) are quoted for the neutral atom. Calculate with the quoted accuracy and enter your answer with the usual 4 significant digits).


First you do this:

(30*1.007825) + (35*1.008665)= 65.538025

Then:

(65.538025-64.924767)*931.5/64.924767 = 8.7986

thank you all~ number 2 was what i needed help with!

can you show your work for the 931.5 MeV conversion factor?

can you show your work for the 931.5 MeV conversion factor?

Delta E = mass difference * c^2

if the mass difference is 1u (1.66E-27) you get

Delta E = 1.66E-27*(3E8)^2 = 1.494E-10 J

1.494E-10J/(1.6E-19 J per eV) = 933750000 eV

933750000/ 10E6 = 933.75 MeV

These are the calculations...for some reason I am getting 933.75 instead of the 931.5 quoted in the notes...