NON-monatomic gas expansion, find internal energy change

[awertag]

Homework Statement

A NON-monatomic gas expands from I to F in the Figure (Since it is not monatomic U=3/2nRT does not give you the internal energy, this only works for monatomic gases, instead you must use the first law). The energy added to the gas by heat is 424 J when the gas goes from I to F along the diagonal path.

(a) What is the change in internal energy of the gas?
Your answer is incorrect.
(b) How much energy must be added to the gas by heat for the indirect path IAF to give the same change in internal energy?

Homework Equations

The Attempt at a Solution

well i tried using ∆U=Q+W(on) and doing all the possible combinations of positive and negative (finding work from area under curve) but I couldn't get the correct answer for ∆U. I hope you can help!

thanks so much
--aweg

 

[member 553083]

tenFor part (a), the change in internal energy of the gas is 424 J. For part (b), the energy added to the gas by heat for the indirect path IAF is 848 J.