Comparing 9.1 and 9.3

[sofiakavanaugh]

Hello,

This is a really simple question but 9.1 and 9.3 appear to use the same equation to calculate entropy but one added a negative sign to the equation before doing the calculation and the other didn't? I was just wondering why.

Thanks!

[Sammy Thatipelli 1B]

In question 1, the entropy is referring to that of the surroundings, which means that the rate of entropy generation will be a negative number. But in question 3, the entropy we are calculating is referring to the system's, and when we talk about deltaS of the system, the deltaS is positive

[Morgan Baxter 1E]

It is important to remember that q(sys)= -q(surroundings).

[Nehal Banik]

It will be negative because you switch the sign in this problem, therefore it makes sense to put it there.