By how much does the entropy of `3` mole of an ideal gas change in going from a pressure of `2` bar to a pressure of `1` bar without any change in Temperature . If the surrounding is at `1` bar and `300` K (Expansion is again of the cosntant extenal pressure of surrounding).

Options

A. `+7.29 J-K^(-1)`
B. `+4.82 J-K^(-1)`
C. `-5.29 J-K^(-1)`
D. `-8.35J-K^(-1)`

Answer

B

Explanation

`DeltaS (gas) = "nR In" (P_(1))/(P_(2)) = 3 xx 8.314 xx "In"2 = 17.29` J/K
Since `DeltaT =0 , "therefore" " " DeltaU =0.`
So, `q=-W`
`="nRT"[1 + (P_(1))/(P_(2))]`
`q=T xx 12.47` J/K
`DeltaS_("surr") =-(q)/(T) =- 12.47` J/K
Change in `DeltaS =+ 4.82` J/K