LearnChemE

Ideal Gas Law: Screencasts

This screencast introduces the concept of ideal gases and how to calculate enthalpy and internal energy changes for an ideal gas.

We suggest you list the important points in this screencast as a way to increase retention.

Explains how, when the temperature changes for an ideal gas, the pressure and volume can change in different ways, depending on constraints.

We suggest you list the important points in this screencast as a way to increase retention.

Optional screencast: Standard Temperature and Pressure – Ideal Gas Law

Important Equations:

Equation of state for an ideal gas:

$PV^t = nRT$

where $$P$$ is the pressure, $$V^t$$ is the total volume (L), $$n$$ is the number of moles, $$R$$ is the ideal gas constant, and $$T$$ is the absolute temperature (K).

Equation of state for an ideal gas (molar volume):

$PV = RT$

where $$V$$ is the molar volume (L/mol).

Enthalpy change of an ideal gas:

$\Delta H = C_P\Delta T$

where $$C_P$$ is the heat capacity at constant pressure, $$\Delta T$$ is the change in temperature from $$T_1$$ to $$T_2$$. This is true for any process, not just one at constant pressure.

Internal energy change of an ideal gas:

$\Delta U = C_V \Delta T$

where $$C_V$$ is the heat capacity at constant volume, $$\Delta T$$ is the change in temperature from $$T_1$$ to $$T_2$$. This is true for any process, not just at constant volume.

The total pressure in a binary mixture:

$P = P_A + P_B$

where $$P$$ is the total pressure, $$P_A$$ is the pressure of gas A, $$P_B$$ is the pressure of gas B.

The mole fraction of A ($$y_A$$) in an ideal gas binary mixture:

$y_A = \frac{P_A}{P}$

Relation between $$C_P$$ and $$C_V$$ for an ideal gas:

$C_P = C_V + R$