Net Increases in Amount of Gas

[MCracchiolo 1C]

Section 9.8 states that a net increase in the amount of gas usually results in a positive entropy change. Is there ever a situation where that is not the case?

[Salman Azfar 1K]

I'd assume that there are more complex systems where things like temperature can affect stuff; however, with the level that we are working at I would pretty much assume an increase in moles of gas is an entropy increase.

[Wenjie Dong 2E]

Not sure. But an increase in the amount of gas increases the moles of molecules and thus increases the possibilities of microstate arrangements, which leads to higher entropy.

[Nehal Banik]

I don't think Dr. Lavelle will ask us any questions where it becomes that difficult, but there is a question in the homework where there are equal moles of gas on both sides of the reaction, and you'd assume that the entropy decreases, but when you use the Gib's free energy values and calculate it, it ends up being negative, so I guess that would be the exception.