Properties of Gases
Physics: Cambridge International GCSE Supplement, topic 2.1.3
Properties of Gases
All gases tend to have similar properties and behave in similar ways.
Temperature of gases
- The higher the temperature of a gas, the higher the kinetic energy of the gas' particles.
- As you heat a gas, you transfer more kinetic energy to the gas' particles.
- This increases the speed of the particles.
Pressure of gases
- A gas exerts pressure on the walls of its container.
- There are lots of gas particles colliding with the container each second.
- When a gas particle collides with the wall of its container, its momentum changes and it bounces back off the wall.
- This exerts a force on both the particle and the wall.
- The pressure exerted on the wall is equal to the force (of the ball) per unit area (of the wall being hit).
Forces
- The pressure exerted on the wall is equal to the force (of the ball) per unit area (of the wall being hit).
- Each particle only exerts a small force on the wall of the container, but the combined effect of many particles colliding with the walls of the container produces a large force.
Absolute zero
- There is a lowest possible temperature, called absolute zero (−273 °C or 0 K).
- At absolute zero, particles have their minimum possible kinetic energy; they do not move at all in the particle model.
- This concept is the basis of the Kelvin temperature scale, where temperature in kelvins is directly proportional to the average kinetic energy of particles.
Test yourself on Properties of Gases
What is the expression for the change in momentum?
A student says that a gas exerts pressure on a container because of the particles colliding with one another in the container, and the particles colliding with the walls of the container.
Is the student correct?