Short Answer

Charles’s law states that the volume of a gas increases when its temperature increases, and the volume decreases when the temperature decreases, provided the pressure remains constant. In simple words, gas volume is directly proportional to temperature. When a gas is heated, its particles move faster and spread out, causing the gas to expand.

This law explains many everyday situations such as why balloons expand in warm air and shrink in cold air. It shows that temperature affects the movement of gas particles, and this change in movement directly affects the space the gas occupies.

Detailed Explanation

Charles’s Law

Charles’s law is an important gas law that explains the relationship between the volume of a gas and its temperature. This law is named after Jacques Charles, a French scientist who studied how gases expand or contract when heated or cooled. According to Charles’s law, the volume of a gas is directly proportional to its temperature when the pressure remains constant. This means that if the temperature of a gas increases, its volume also increases. If the temperature decreases, the volume decreases as well.

This direct relationship helps us understand why heating causes gases to expand and why cooling causes gases to contract. Charles’s law is widely used in studying gas behaviour in chemistry and also helps explain many natural and daily life processes related to temperature changes.

Direct Relationship Between Volume and Temperature

The main idea of Charles’s law is that volume and temperature change together in the same direction. When temperature rises, gas particles gain more kinetic energy, move faster, and spread out, causing an increase in volume. When temperature decreases, particles slow down and come closer, causing the gas to occupy less space.

This relationship can be written as:
V ∝ T (Volume is directly proportional to temperature)
But temperature must always be measured in Kelvin for this law to work correctly.

Why Charles’s Law Works

To understand why this law works, we must look at the behaviour of gas particles. Gas molecules are always in constant random motion. Their movement depends on their kinetic energy, which is directly linked to temperature.

When temperature increases:

• Gas particles move faster.
• They collide with more force.
• They spread apart to make more space.
• This increases the volume.

When temperature decreases:

• Particle motion slows down.
• Collisions become weaker.
• Particles come closer.
• The gas occupies less space.

Since pressure is kept constant, the only way to balance these changes in motion is by changing the volume. This is why gases expand or contract with temperature.

Mathematical Expression of Charles’s Law

Charles’s law can be written as:
V₁ / T₁ = V₂ / T₂

Where:

• V₁ = initial volume
• T₁ = initial temperature
• V₂ = final volume
• T₂ = final temperature

This equation shows that the ratio of volume to temperature remains constant if pressure does not change.

Everyday Examples of Charles’s Law

Charles’s law applies to many situations in daily life:

1. Hot Air Balloons:
   When air inside the balloon is heated, it expands and becomes lighter than the surrounding cold air. This causes the balloon to rise.
2. Balloons Shrink in Cold:
   A balloon kept in a cold place shrinks because the air inside contracts as temperature decreases.
3. Car Tyres in Winter:
   Tyres appear slightly deflated during cold weather because the air inside contracts due to lower temperature.
4. Bursting of Gas Containers in Heat:
   In hot conditions, gases expand. If the volume is restricted, pressure increases, which can cause containers to burst.
5. Aerosol Cans:
   Cans kept in sunlight can expand or burst because the gas inside heats up and expands.

These examples show how temperature directly affects gas volume in everyday life.

Scientific Importance of Charles’s Law

Charles’s law is used in designing many scientific instruments and understanding atmospheric processes. It helps explain weather changes, gas expansion in engines, and behaviour of gases in laboratories. It also helps pilots, mountaineers, and divers understand how gases behave at different temperatures.

The law is a fundamental part of the combined gas law and contributes to understanding the ideal gas equation, both of which are important tools in chemistry and physics.

Conclusion

Charles’s law states that the volume of a gas is directly proportional to its temperature when pressure is kept constant. This means that gases expand when heated and contract when cooled. The law explains many daily life observations and is important in understanding the behaviour of gases in scientific and practical situations. It shows how temperature affects the movement and spacing of gas particles.