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

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

Question

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

lolaismy · Answer

When a gas expands against a pressure, then the system is doing work on the surroundings. I think you should take a look at the first law of thermodynamics to get a better understanding because this can be quite a tricky subject!

vera_ewing · Answer

Okay, so which one do you think the answer is?

lolaismy · Answer

Well  when work is done on a system, the internal energy is increased! Compressing a gas inside a thermally insulated container increases the internal energy of the gas.

lolaismy · Answer

let me review over the answers this is very tedious haha

lolaismy · Answer

I don't want to give you the wrong answer, let me review over my chem notes

vera_ewing · Answer

I think it's either A or B. @JFraser What do you think?

jfraser · Answer

$$W_{sys} = -P*\Delta V$$

jfraser · Answer

work doen $by$ a system is energy $lost$ by the system to the surroundings as work

lolaismy · Answer

I would honestly say it's D but I'm not too sure. It is work done to the system, but the energy is lost to the system