Effects of Temperature and Pressure on Volume of a Gas | Chemistry for Grade 11 (IGCSE) PDF Download

Pressure & Temperature in Gases

• Changes in temperature or pressure impact how much space gases take up
• When the interior of a hot air balloon is heated, it enlarges, causing the balloon to increase in size
• This occurs because the volume of a gas rises with its temperature

• When a gas is confined in a container and the volume is reduced through compression, the pressure of the gas increases.
• This phenomenon is akin to what occurs in a bicycle pump.
• By compressing the bicycle pump, the elevated pressure enables the inflation of a tire.
• The impact of this high pressure can be felt when placing a finger on the pump's end.

Gases and Kinetic Theory

• Gaseous particles are in constant, random motion within a container.
• This motion generates pressure by the particles colliding with the container walls.
• Visualize molecules in a gas bouncing off each other and the container walls, creating pressure in the process.
• The pressure exerted by a gas is a result of the continuous, energetic movement of its particles.

• Kinetic Energy: When the temperature of a gas increases, the kinetic energy of its particles rises. For instance, think of a pot of water on a stove. As the heat is turned up, bubbles form at the bottom and rise to the surface faster.
• Frequent Collisions: Imagine a balloon being inflated. As it expands, the rubber stretches. Similarly, when gas particles gain energy and move faster, they collide with the container walls more frequently, exerting pressure.
• Container Flexibility: A rubber balloon expands when filled with hot air, showcasing how flexible walls accommodate increased particle movement.
• Volume and Pressure: If you squeeze an air pump, reducing its volume, you will notice an increase in the pressure required to compress it further. This demonstrates the inverse relationship between volume and pressure in gases.