1. The problem statement, all variables and given/known data 2.1E5 J of heat enters an ideal gas as it expands at a constant T = 77°C to four times its initial volume. How many moles of gas are there? T=350K, Q=2.1E5 J, Vi=x, Vf=4x 2. Relevant equations ΔU=Q-W W=[itex]\int[/itex]pdV U=nCvT 3. The attempt at a solution I'm not sure if I'm even on the right track here. I have W=[itex]\int[/itex]pdV = nRT[itex]\int[/itex]dv/V = nRTln(Vf-Vi) I am stuck here because I need to know n to solve for work but I need to know W to solve for n. I am clearly missing something but I can't figure out what it is.