"Jose" wrote in message
et...
My point was that I don't understand where the confusion is as to where the
heat comes from in filling a scuba tank. You are cramming a whole crapload of
molecules into a confined space and it makes heat.

Yes, but you are cramming a whole crapload of =cold= molecules into that
space. The heat generated seems like it wouldn't be enough to compensate for
the cold of the inflowing gas.

That gas is cold because it expanded from the other tank, which was under even
higher pressure.

The gas in the tank that is expanding has all of the cold being produced, shared
among all of the gas in the tank, not just the gas that is leaving the tank.

If the cold was contained in, and limited to just the molecules that were
leaving, then the tank being compressed might not get hot. That is not
happening though, and much of the cold is left behind in the now, very cold
tank.
--
Jim in NC