# 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.- The Clausius Inequality

- Entropy: A New Property

- The Principle of Increasing Entropy

- Fundamental Property Relationships

- Polytropic and Isentropic Processes

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