Ch 7 - Entropy

Here we present a discussion of the

Clausius Inequality

as it applies to reversible and irreversible processes.

In this lesson, we define

entropy

, show how to obtain entropy data from the

NIST WebBook

and introduce an important new phase diagram: the

TS Diagram

. We show how and why the TS Diagram is particularly useful for the analysis of

thermodynamic cycles

.

We use the

Clausius Inequality

and the definition of

entropy

to set the stage for the introduction of

entropy generation

. We show that the area under an irreversible process path on a TS Diagram is not equal to the heat transferred during the process. We conclude by showing that the

Principle of Increasing Entropy

is true: The

entropy of the universe

cannot decrease.

In this lesson, we derive the

1st and 2nd Gibbs Equations

. We show how they can be used to evaluate for processes involving incompressible substances and ideal gases.

In this lesson, we introduce

relative volume

and

relative pressure

. Then we discuss

isentropic

processes on ideal gases in which the heat capacities are constant. This turns out to be a special case of the more general

polytropic process

. We then show how to calculate the boundary work for polytropic processes in closed systems. We conclude by showing that

an isentropic compression

of an ideal gas requires the least work.