Stupid physicists.
Oct. 28th, 2003 04:31 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
elwenSo our question on the homework involves the heating of an ideal gas by two different pathways. Our starting volume is 22.4L, which just happens to be the molar volume of an ideal gas at STP. This is convenient because then we can use molar heat capacities without worrying about n. There's only one problem. We are not at STP. We are, in fact, at what must have been what they had in mind by "normal temperature and pressure" on the quiz yesterday: 1 atm pressure and "300°K". So we don't really have 1 mole but 0.9099 moles. I'm just waiting for the solution set to say we have 1 mole anyway by invoking STP.
So since we don't have STP, we must calculate the number of moles. We still have a problem: we have no idea how to convert between atm and mks units, and our lovely not-text Feynman doesn't give you any constants or conversion factors whatsoever. So our values for k and P are incompatible. Beyond this, the problem just seems set up for using moles when we never use moles or R in physics. And you must admit that finding heat capacities per particle would be rather unwieldy. (Not that k isn't to begin with, in my opinion.)
All these observations make me suspect that the question was ripped off of some chemistry problem and then bastardized by the application of physics' not-STP.
So since we don't have STP, we must calculate the number of moles. We still have a problem: we have no idea how to convert between atm and mks units, and our lovely not-text Feynman doesn't give you any constants or conversion factors whatsoever. So our values for k and P are incompatible. Beyond this, the problem just seems set up for using moles when we never use moles or R in physics. And you must admit that finding heat capacities per particle would be rather unwieldy. (Not that k isn't to begin with, in my opinion.)
All these observations make me suspect that the question was ripped off of some chemistry problem and then bastardized by the application of physics' not-STP.
