1. The problem statement, all variables and given/known data Okay so I'm trying to figure out how to get this answer. Theres a souffle made of some ingredients and filled with these ingredients along with some air. Everything starts off at 283.15 K and gets heated in the oven to 463.65 K. Also assume that the air expands with heat as an ideal gas, and the other ingredients' expansion is negligible. Also the volume after heating up is 1.4 times the volume before heating up. What we are looking to find is the fraction of the volume of the souffle that is air before being heated up, and the fraction of the volume of the souffle that is air after being heated. 2. Relevant equations PV=T PV=nRT Vtotal=Vair+Vother therefore Vtotal-o=Vair-o+Vother Vtotal-f=Vair-f+Vother also Vother-o=Vother-f Vtotal-f=1.4Vtotal-o 3. The attempt at a solution So I've messed around with these known equations and legitimately came up with something that I feel is in the right direction of solving the problem. I found that 1=(Vair-f - Vair-o)/0.4. I figure now that I can use PV=T to get this formula in terms of one variable of the air's volume, however I am not really sure how to do that since I have no value for P. I'm assuming also in this problem that being a souffle, when it heats up the top just tightens to keep the pressure constant. So that's all I got. If somebody could help or point me in the right direction for solving this that would be awesome.