posted by Mima on .
For the following fusion reaction, Calculate change in energy per mole.( Answer in J/mole)
2H1 + 2H1 ---> 3H1 + 1H1
(the mass number is in front of the atom and the atomic number is behind the atom)
Given info:Atoms with their masses(amu)
I know delta E=(C^2)(delta m)
and I know delta m= products mass- reactants mass
and I know 1 amu = 1.661X10^-27 Kg
I got delta E= -0.297 x 10^-6 but still my answer is wrong.
You didn't show all of your work and I've not been able to obtain your same numbers. One possible problem may be the amu conversion.
I think mass = 4.02387 on the right and 4.02820 on the left. delta m = 4.33E-3 amu/atom which = 4.33E-3 g/mol and we convert that to kg (4.33E-6) and multiply by c^2 (3E8 m/s squared). You may want to use a more precise value for c. See if that won't give you the ok.
I'm getting 8.355E-22 Kg on for reactants, and 8.322E-22 Kg for products.
I multiplied each mass they gave us in amu by 1.661E-27 to get it in Kg.
You can do that (it's a lot of extra work) but when you finish you have kg/atom and you must multiply all of that by 6.02E23 to obtain kg/mol. However, I still don't obtain your numbers. When done your way you open yourself up to a lot of rounding errors.
Try what I outlined above and see if it isn't simpler. In fact, I never use the 1.661E-27 factor BECAUSE it cancels out if we want J/mol.
amu/atom x (1g/6.022E23 amu) x (6.022E23 atom/mol) = grams/mol. Note that 1g/6.022E23 (the second term) = 1.661E-24 g/amu which is where the 1.661E-27 kg/amu comes from.