Gas Laws: Boyle's, Charles', and Pressure Law

Introduction to Gas Laws

Gas laws describe how gases behave under different conditions of pressure, volume, and temperature. These laws are crucial for understanding the properties of gases and are explained using the kinetic theory of gases.

Boyle's Law

Boyle's Law states that the pressure of a gas is inversely proportional to its volume when the temperature is kept constant. Mathematically, it is expressed as:

$$P \propto \frac{1}{V} \quad \text{or} \quad PV = k$$

• P is the pressure of the gas.
• V is the volume of the gas.
• k is a constant for a given mass of gas at a constant temperature.

This means that if the volume of a gas decreases, its pressure increases, provided the temperature remains unchanged.

Verification of Boyle's Law

Boyle's Law can be verified using a simple apparatus like a syringe and a pressure gauge. By compressing the gas in the syringe and measuring the pressure, you can observe the inverse relationship between pressure and volume.

Charles' Law

Charles' Law states that the volume of a gas is directly proportional to its absolute temperature when the pressure is kept constant. It is mathematically represented as:

$$V \propto T \quad \text{or} \quad \frac{V}{T} = k$$

• V is the volume of the gas.
• T is the absolute temperature (in Kelvin).
• k is a constant for a given mass of gas at constant pressure.

This means that as the temperature of a gas increases, its volume also increases, provided the pressure remains constant.

Verification of Charles' Law

Charles' Law can be verified by heating a gas in a sealed container and measuring the change in volume with temperature, ensuring the pressure remains constant.

Pressure Law

Pressure Law (also known as Gay-Lussac's Law) states that the pressure of a gas is directly proportional to its absolute temperature when the volume is kept constant. It is expressed as:

$$P \propto T \quad \text{or} \quad \frac{P}{T} = k$$

• P is the pressure of the gas.
• T is the absolute temperature (in Kelvin).
• k is a constant for a given mass of gas at constant volume.

This indicates that if the temperature of a gas increases, its pressure increases, provided the volume remains constant.

Verification of Pressure Law

The Pressure Law can be verified by heating a gas in a rigid container and measuring the pressure changes as the temperature increases.

Worked Example