Chapter 14: Thermal Physics

Ideal Gas

A theoretical gas composed of many randomly moving particles that do not interact except through elastic collisions.

Pressure

The amount of force applied to a surface, measured in N/m², pascals (Pa), or kilopascals (kPa).

Gas Laws

Boyle's Law

The volume and pressure of a gas are inversely proportional if the temperature remains constant. Formula: $P_1{V}_1=P_2{V}_2$

Charles's Law

The volume and temperature of a gas are directly proportional if the pressure remains constant. Formula: $\frac{V_1}{T_1}=\frac{V_2}{T_2}$

Gay-Lussac's Law

The pressure and temperature of a gas are directly proportional if the volume remains constant. Formula: $\frac{P_1}{T_1}=\frac{P_2}{T_2}$

Combined Gas Law

The relationship between pressure, volume, and temperature of a gas. Formula: $\frac{P_1}{T_1}{V}_1=\frac{P_2}{T_2}{V}_2$

Ideal Gas Law

Formula

$PV=nRT$

Variables

• P: Pressure (Pa).
• V: Volume (m³).
• n: Number of moles.
• R: Universal gas constant (8.31 J/(mol·K)).
• T: Temperature (K).

Questions for Students

1. State Boyle's Law and explain its significance with an example.
2. Define Charles's Law and explain why temperature must be in Kelvin.
3. Explain Gay-Lussac's Law and its relationship between pressure and temperature.
4. What is the formula for the Ideal Gas Law, and what do each of its variables represent?
5. How do real gases deviate from ideal gas behavior?