Gchem Q

[prsndwg]

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Can someone explain this to me please..

 

[wantVCUdental]

Can someone explain this to me please..

answer is C, because at extremely high pressures, the volumes of molecules come in to play.
Methane is none polar, so i don't think intermolecular forces is huge here... van der wals is only significant for large molecules

 

[Denty8]

Can someone explain this to me please..

I agree C is the right answer, mol volume causes the greatest deviation from ideal gases.

What program are these questions from?
Thanks

 

[AmpedUp]

I suck at gas law stuff. However, if I remember correctly, at Ideal conditions, pressure is low and temperature is high. Using that principle, "A" seems like a reasonable answer. Can anyone tell me if I'm right or wrong on this one?

Deviation to Ideal conditions = High Pressure, Low Temp...which would amount to a greater ratio than at ideal

 

[Bizzlers]

Can someone explain this to me please..

Answer: D

Ignore the phrase "at moderately high pressures"...this is just extraneous information. What is important is that the problems states that the PV/RT ratio for one mole of gas is less than one. PV/RT = n, so the ratio is less than expected. The only way to account for this difference is intermolecular forces.

It is assumed that ideal gases are point particles. A deviation in ideal behavior where molecular volume dominates would give a PV/RT of greater than one for one mole of methane.

 

[redchesus]

It is assumed that ideal gases are point particles. A deviation in ideal behavior where molecular volume dominates would give a PV/RT of greater than one for one mole of methane.

Yeah, but the question isn't about an ideal gas, it's asking how methane acts in relation to an ideal gas

I actually think the answer is C, because high pressure means smaller container volume, which means the size of the molecules become important (ideal behavior is LOW pressure)

EDIT: I actually found something that illustrates exactly that: http://library.thinkquest.org/C006669/media/Chem/img/PV.gif

prsndwg, is there an answer key?

 

[prsndwg]

the answer key explains exactly what wantVCUDental says

 

[winnie bear]

I suck at gas law stuff. However, if I remember correctly, at Ideal conditions, pressure is low and temperature is high. Using that principle, "A" seems like a reasonable answer. Can anyone tell me if I'm right or wrong on this one?

Deviation to Ideal conditions = High Pressure, Low Temp...which would amount to a greater ratio than at ideal

That's where you have to be careful on multiple choice Q's. Even if the statement were true, make sure it answers the question. But as far as what you're asking, like you said on the last part, real gases deviate from idea when pressure is high (intermolecular forces softens the impact of collisions) so for "A" to be a correct statement, it should say that at LOW pressure, the gas behaves ideally so "A" is false.

 

[Bizzlers]

Yeah, but the question isn't about an ideal gas, it's asking how methane acts in relation to an ideal gas

I actually think the answer is C, because high pressure means smaller container volume, which means the size of the molecules become important (ideal behavior is LOW pressure)

EDIT: I actually found something that illustrates exactly that: http://library.thinkquest.org/C006669/media/Chem/img/PV.gif

prsndwg, is there an answer key?

Yes, the question is not about an ideal gas. The question is about a real gas in relation to predictions for ideality. I still stand by my answer and your book may be wrong. Take a look at this: http://ndtvtutor.topiitcoaching.com/article/article/show/57/Deviation-from-Ideal-Behaviour-by-Gases

I believe the answer to your question is in the first section.