- #1
nonequilibrium
- 1,439
- 2
Hello. I'm trying to thoroughly grasp Thermodynamics, so I'm looking into it again, starting from scratch.
1) Quite early, I had a question with something very commonly taught. If you double the volume of a gas (the temperature is taken as a constant), the pressure becomes half its original value. Pressure is defined as F/A, and as T = constant => v = constant => no change in momentum => no larger/smaller force, so the only variable that changes in the defintion of pressure is the area A. However, to get the new pressure, the area has to be twice as large if you fill it in, in the defintion. But of course, if you double the volume, this doesn't mean you double the area. So... How come pressure really does become half as large?
2) I find it quite confusing how ideal gasses and realistic ones are used through each other. I'm uncertain about the definition of temperature. So temperature only is proportional to the internal energy with ideal gasses? Temperature only says something about the moving of the particles, right? And the internal energy also says something about the intermolecular forces. Does temperature also include vibration and rotation? How come there are different specific heats? Is this due to the presence of realistic gasses? Would it be a constant for ideal gasses? And are they different because the intermolecular forces are different + different masses?
Sorry for unloading a lot of question rapidly after each other, but I'm having trouble truly understanding it all. I'm learning myself thermodynamics using the hyperphysics site, should that work? Other helpful sites are always welcome...
1) Quite early, I had a question with something very commonly taught. If you double the volume of a gas (the temperature is taken as a constant), the pressure becomes half its original value. Pressure is defined as F/A, and as T = constant => v = constant => no change in momentum => no larger/smaller force, so the only variable that changes in the defintion of pressure is the area A. However, to get the new pressure, the area has to be twice as large if you fill it in, in the defintion. But of course, if you double the volume, this doesn't mean you double the area. So... How come pressure really does become half as large?
2) I find it quite confusing how ideal gasses and realistic ones are used through each other. I'm uncertain about the definition of temperature. So temperature only is proportional to the internal energy with ideal gasses? Temperature only says something about the moving of the particles, right? And the internal energy also says something about the intermolecular forces. Does temperature also include vibration and rotation? How come there are different specific heats? Is this due to the presence of realistic gasses? Would it be a constant for ideal gasses? And are they different because the intermolecular forces are different + different masses?
Sorry for unloading a lot of question rapidly after each other, but I'm having trouble truly understanding it all. I'm learning myself thermodynamics using the hyperphysics site, should that work? Other helpful sites are always welcome...