13. Quantification of Entropy and T-S diagrams

Question 1

True or false:

Entropy is a state variable.

Answer 1

True:
We can see below that if there is a set of processes done, and its reversible, the entropy will be changed by a set amount then. The entropy for both paths will be the same amount.

Question 2

What are the two common entropy equations?

think pressure and volume being…

Answer 2

Note: we used entropy definition and first law to derive the Tds equations. They apply to both reversible and irreversible processes. (remember isothermal process has entropy change, but can be reversed).

Question 3

What are the four processes represented on a T-S diagram? What are there equations for entropy?

Answer 3

Note: adiabatic is isentropic process