High and Low Pressure vs Entropy

[Ian_Lee_1E]

Hello,

I am getting confused with the comparison of same gas in different pressure in their entropy values.

I guess I'm thinking of entropy as a more chaotic substance but I think I am wrong because I've been thinking that greater pressure leads to greater entropy since gas molecules will move at higher speed, leading to more chaos in the volume.

For every comparison of pressures, do we have to assume that the volume will change since it does not state that they are in constant volume? Also, if they are in the same volume and the pressure is different, which one has greater entropy?

[kateraelDis1L]

I remember this example from a book question that asked. Which substance has the higher molar entropy? 1.0 mol Ar(g) at 1.0 atm or 1.0 mol Ar(g) at 2.0 atm. The answer is at 1.0 atm because it will occupy larger volume than that at 2 atm. Hope this helps.

[Marisa Gaitan 2D]

Entropy generally increases as pressure decreases (as a result of a volume increase) due to the greater availability of positions (microstates) the particles can take.

[DavidTabib 3H]

As volume decreases, pressure tends to increase due to their inversely related relationship.