Under constant pressure, a system of gases is sealed in a cylinder and then compressed. What can you conclude about the work associated with this change?

A. Work is positive and is done to the system.
B. Work is negative and is done by the system.
C. Work is positive and is done by the system.
D. Work is negative and is done to the system.

Question

Under constant pressure, a system of gases is sealed in a cylinder and then compressed. What can you conclude about the work associated with this change?

 		A.	Work is positive and is done to the system.
 		B.	Work is negative and is done by the system.
 		C.	Work is positive and is done by the system.
 		D.	Work is negative and is done to the system.

vera_ewing · Answer

@sweetburger please help me!

unklerhaukus · Answer

i think the cylinder of gas is being cooled

unklerhaukus · Answer

which means it's loosing energy, 

so the process doing this, must be working on the system, in the negative sense

matt101 · Answer

This is a case of pressure-volume work, where W=PΔV.

According to the question, the gas is compressed. That means ΔV is negative, which makes work negative (pressure is always a positive value). If work is negative, that means work was done ON the system, rather than BY the system.

That makes D your answer.

vera_ewing · Answer

Thank you so much! :)