Self-test 4F.5A

[Alvin Lai 3J]

Calculate the change in entropy when the volume of 2.00molAr(g) is decreased from 10.00 L to 5.00 L, while the temperature decreases from 300. K to 100. K. Assume ideal behavior.
The answer is −38.9J⋅K−1, but I do not know how to get it. Can someone explain how to do this?

[Amanda Chang 2B]

Since both temperature and volume are changing, you would have to calculate the change in entropy associated with both changes and add both changes in entropy to find the total change in entropy.

[Frankie Mele 3J]

First use the equation delta S = n*Rln(v2/v1) to find the change in entropy for the volume change. Then use the equation delta S = n*Cln(t2/t1) to find the change in entropy due to the temperature change. Lastly, you can add these two values to get the answer:)