1. The problem statement, all variables and given/known data Ok, I'm a little confused about the connection between pressure and temperature. Let's take two scenarios: 1) I have a ballon filled with helium at 30 degrees, and then I put it in the freezer. Then the volume changes, but the pressure stays constant, right? 2) I have the following setup: http://peecee.dk/upload/view/98728 The two buckets have different temperature - so the gas inside the hose has different temperatures at the sides 1 and 2. But why isn't the volume in part 1 bigger than the volume in part 2? Is that because the pressure is not constant? I can't quite figure these things out. Thanks in advance, sincerely Niles.