Does a gas canister change temperature as gas is released? If you have a deodorant can, it is obvious that the gas leaving the can has cooled as it expands. However, is there also a change of temperature of the gas that remains within the canister?
My assumption is that it would also cool down, but by a lesser amount. My reasoning being that as the gas is released, there is now less gas remaining in the canister, so the pressure within the canister has reduced and the gas within the canister has expanded. However, as the change in pressure is less than that of the released gas, the change in temperature will also be less.
Is my assumption correct?
 A: Yes, it will cool, but not by a lesser amount. It's actually a much greater amount. You can test this by holding the can and spraying out a lot of deodorant. It gets colder. (Unless you ignite the spray, but let's not do that. Not again - it's dangerous!)
As pointed out in the cool (geddit) video that Aaron linked to, the propellant is a combination of liquid and gas, and it's the endothermic changing of liquid to gas phase to maintain equilibrium in the can that cools the can. As you will see, the pressure does not decrease until the can is almost empty.
A: Your assessment of the temperature decrease in the canister is correct.  But, it is not "by a lesser amount."  It is actually the dominant cooling.  The gas flow through the valve takes place at constant enthalpy, and, for an ideal gas, this would involve no temperature change.  This is because the expansion cooling of the gas in the valve is offset by viscous heating in the valve.  This is called the Joule-Thomson effect.
A: The gas inside the can will experience an expansion. If the process is very rapid, the expansion is an adiabatic process, where both pressure and temperature drop.
