So here I am at work, and the go-to people for physics are away. Here is the problem I am trying to figure out: I'm wondering how much energy it takes to compress a certain amount of air at a certain temperature, to a certain pressure. For example, lets say I had a 4-gallon tank of STP air and I wanted to add air until the pressure inside the tank reached 300 kPa. How much energy, in joules, would it require to do this? -Dan edit: nevermind this thread. Zz gave me a bit of help. If you want, you can still give me some help, but for now, I should be fine, unless I post here again requesting help.