Ideal Gas

Definition

Molecules are spaced far enough apart that intermolecular forces are negligible

Equations

$PV=mRT$
$PV=nRT$
Using the molar mass of a given gas, you can turn R into a mass-based constant.

When does the Ideal gas law apply?

Read gasses approximate as ideal gas when it is dilute:

• Low density
• Low P and high T

Z as an ideal gas correction factor
$Z=\frac{P{v}_{actual}}{RT}=\frac{v_{actual}}{v_{ideal}}$
For an ideal gas, Z = 1
For an easily compressible gas, Z < 1
For a gas that is hard to compress, Z > 1

How to Find Z

• Look in table A1 to find the critical pressure, then look at your pressure and compare the two.
• Then you can see if you act ideally or not according to the below

Acting Ideally

if P << P_cr we act ideally if T >> T_cr we act ideally

You can calculate reduced pressure with the following:
$P_r=\frac{P}{P_{Cr}}$ Then you can use P_cr and T_cr to find Z using the chart in the properties table booklet!