Lesson Overview

In the previous lesson, we derived the following two forms of the 1st and 2nd

Gibbs Equations

for ideal gases.

1st Gibbs Equation (Ideal Gas)

2nd Gibbs Equation (Ideal Gas)

Equation.
Equation.
In this lesson, we will apply these equations to

isentropic

processes. This will lead us to define the

relative volume

and

relative pressure

, Vr and Pr. These functions are tabulated along with So in the

Ideal Gas Entropy Tables

for some common gases.
Then, we will consider special

isentropic

processes in which the

heat capacities

of our ideal gases are constant. This will lead to three helpful relationships between P, V and T.
Finally, we turn our attention to

polytropic

processes. These processes can include

irreversible

processes as well as systems that contain real fluids as well as ideal gases. We will find that an

isentropic

process on an ideal gas with constant heat capacities is a special case of the more general

polytropic

process. We will also see that

isothermal

,

isobaric

and

isochoric

processes can also be considered to be special cases of the

polytropic

process.
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Ch 7, Lesson E, Page 1 - Lesson Overview