Second Law

[Jared Smith 1E]

When would we use the equation of the second law delta S=q (rev)/T? I can't seem to find a lot of example problems that use it directly. Is it meant to be used frequently for calculations, or mainly as a means of deriving the other equations we learned in lecture?

[Jiun Yue Chung 2I]

If you look at example 9.1, it tells you that you can use that same equation to calculate the change in entropy when a system is being heated (reversibly). So if the question says that at constant temperature, a system is gaining some amount of energy in joules, it should be safe to use this formula.

[Stephanie tran 1J]

the equation wasn't specifically used in many examples as only example 9.3 used the equation directly, but the equation is derived to attain the equations for entropy change when there's a change in temperature with constant volume or pressure, and for entropy change of an ideal gas when it expands isothermally changing from one volume to another.