Consider a fire syringe similar to the one you used in Section 18.5. It was assu

Question

Consider a fire syringe similar to the one you used in Section 18.5. It was assumed that when the plunger is pushed in very quickly, the gas compression is adiabatic. What is an adiabatic compression? Is it reasonable to assume the compression is adiabatic? Why or why not? Is it reasonable to assume the compression is adiabatic when the plunger is moved into the glass tube very slowly? Why or why not? Do you think a significant proportion of the air molecules are leaking out of the tube when the air is being compressed? Why or why not.

Explanation / Answer

a) An adiabatic process is defined as one with no heat transfer into or out of a system; Q=0. Hence detlaU=-W. So, an adiabatic compression happens when a gas becomes compressed without heat transfer in the system. b) I can't see the figure, but I googled what a fire syringe was. Yes, you can assume it. Why? Because the gases inside it compress so rapidly that there is no time for them to exchange heat with their surroundings. Hence, the expansion is adiabatic. As the compressing gases get work done by their surroundings, their internal energy and temperature both rise. c) No because as I explained before, it needs to happen rapidly. If it happened slowly, the gases would have time to exchange heat with their surroundings. d) No because we're assuming everything is ideal. If they were not and it was the real world, a small amount would leak out and it would depend on the quality of the fire syringe too.

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