StarTurtle

Hey there everyone. My Chemistry grade is not so hot right now, and this test basically decides my final grade. ^^; So I really want to get it right, so if you could help me out a little, it would be greatly appriciated. So, here's the thing: I got very sick last week and missed four classes. This means I missed almost all of the lessons for thermochem. Because of this, I have no clue what I'm doing. My current and biggest issue is something about Hess's Law. Anyone think they can help me with it? Mainly, I don't know how I'm allowed to cancle things out and how I'm not allowed to. If someone could explain that to me, or if I could just enter in my problem and have some of you guys look at it, it would probably help a whole bunch.