AQA GCSE HIGHER PHYSICS - Pressure in Gases and Volume Changes

AQA GCSE Higher Physics: Pressure in Gases and Volume Changes

Introduction:

This tutorial will explore the relationship between pressure and volume of a gas at a constant temperature. We'll delve into the Boyle's Law concept and its applications.

Boyle's Law:

Boyle's Law states that for a fixed mass of gas at a constant temperature, the pressure and volume are inversely proportional. This means that as the pressure increases, the volume decreases proportionally, and vice versa.

Mathematical Representation:

The relationship between pressure and volume can be expressed mathematically as:

Pressure * Volume = Constant 

This is often written as:

P?V? = P?V?

Where:

• P? = Initial pressure
• V? = Initial volume
• P? = Final pressure
• V? = Final volume

Understanding the Formula:

• The formula implies that the product of pressure and volume remains constant for a fixed mass of gas at a constant temperature.
• If the pressure is doubled, the volume will be halved.
• If the volume is tripled, the pressure will be reduced to one-third of its initial value.

Applications of Boyle's Law:

Boyle's Law has various applications in everyday life and scientific fields:

• Diving: Divers need to understand Boyle's Law to calculate the pressure changes experienced at different depths.
• Medical Equipment: Boyle's Law is applied in the design of syringes and other medical devices that use gas pressure.
• Engines: The combustion process in engines relies on Boyle's Law to convert the heat energy from burning fuel into mechanical energy.
• Weather Forecasting: Boyle's Law helps meteorologists understand and predict weather patterns.

Example Problem:

A gas occupies a volume of 2.0 liters at a pressure of 1.5 atmospheres. What will be its new volume if the pressure is increased to 2.5 atmospheres, keeping the temperature constant?

Solution:

Using the formula P?V? = P?V?:

• P? = 1.5 atmospheres
• V? = 2.0 liters
• P? = 2.5 atmospheres
• V? = ?

Substituting the values in the formula:

1.5 * 2.0 = 2.5 * V?

Solving for V?:

V? = (1.5 * 2.0) / 2.5 = 1.2 liters

Therefore, the new volume of the gas will be 1.2 liters.

Conclusion:

Boyle's Law explains the inverse relationship between pressure and volume of a gas at a constant temperature. This fundamental law has significant implications in various scientific and everyday applications. Understanding Boyle's Law is crucial for comprehending the behavior of gases and their interactions with the environment.