Ideal Gas Law and Gas Behavior Q

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mist.illusionist
Posts: 17
Joined: Mon Jan 28, 2019 9:21 am

Ideal Gas Law and Gas Behavior Q

Post by mist.illusionist » Tue May 07, 2019 5:24 pm

Which of the following changes to a sealed, flexible container of gas would have an ambiguous effect on its volume?
- lowering T while increasing P
- raising T while decreasing P
- decreasing P while injecting more gas into the container
- raising T while increasing P

I got this one wrong, and it did not tell me which one is the right answer and why. Thank you.
NS_Tutor_Will
Posts: 693
Joined: Fri May 25, 2018 9:15 am

Re: Ideal Gas Law and Gas Behavior Q

Post by NS_Tutor_Will » Wed May 08, 2019 10:31 am

Thanks for the question!

So the easiest way to tackle this one is to think about which direction, in terms of volume change, each of the possible changes would have. Since we're looking for an ambiguous one, we want two changes that lead to opposite outcomes. Below, I'll lay out what each of the following changes (while other factors are held constant) would do to the volume

Increasing temperature --> larger volume
Decreasing temperature --> smaller volume
Increasing pressure --> smaller volume
Decreasing pressure --> larger volume
Increasing number of moles --> larger volume
Decreasing number of moles --> smaller volume

Based on the options presented, lowering T and increasing P wouldn't be ambiguous since both would promote a smaller volume. Decreasing P and increasing number of moles would both promote a larger volume, so this can't be right either. Raising T and lowering P would both promote a larger volume as well, so this wouldn't be ambiguous. Only the last option, raising T and increasing P would promote opposite effects (larger volume and smaller volume, respectively).

I hope this makes sense! Good luck!
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