1. The problem statement, all variables and given/known data http://img694.imageshack.us/img694/9990/fig24a.jpg" [Broken] The scenario is, the water in the beaker = system 1. Everything else, including walls = system 2. The bunsen burner heats the water in the beaker. dU or the change in internal energy of system 2 decreases. dT or the change in temperature of system 2 increases. How can this be possible? 3. The attempt at a solution I thought about this for a while. My bad hunch and how I would answer this on a test is that....system 1 increases in temperature and heat is transferred from the bunsen burner to system 1. However, heat is transferred back into system 2 because the bunsen burner is only part of system 2. This is what happens as both systems try to reach equilibrium. I still don't know why the temperature of system 2 would increase though. To be honest, I don't even know what system 2 is referring to when in relation to temperature, is it referring to the average temperature of the surroundings (air, bunsen burner, atmosphere, etc.). I'm really confused as you can tell, someone please help!