3.3.1

Particle Motion in Gases

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States of Matter

There are 3 different states of matter.

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Solids

  • A solid has a fixed shape because of the strong forces between its particles.
  • Solids cannot be compressed because their particles are already very close together and cannot flow.
  • The particles in a solid are arranged in an ordered pattern.
  • The particles in a solid move around a fixed point.
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Liquids

  • Liquids cannot be compressed because their particles are already very close together.
  • In a liquid, the particles are in contact with one another, but they can still move. This allows a liquid to flow and take the shape of its container.
  • Particles in a liquid are arranged in a disordered pattern.
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Gases

  • Gases can be compressed because their particles are very far apart.
    • When water evaporates to become steam (gas), its volume increases by 1000x.
  • The particles in a gas are free to move in any direction. Because of this, a gas can flow, has no fixed shape and completely fills its container.
  • The particles in a gas move randomly and are not organised in any way.

Properties of Gases

All gases tend to have similar properties and behave in similar ways. For a fixed mass of gas at a constant temperature, pressure x volume is constant.

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Temperature of gases

  • The higher the temperature of a gas, the higher the kinetic energy stored in the gas' particles.
    • As you heat a gas, you transfer more kinetic energy to the gas' particles.
    • This increases the speed of the particles.
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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).

Jump to other topics

1Energy

2Electricity

3Particle Model of Matter

4Atoms & Radiation

5Forces

6Waves

7Magnetism

8Astrophysics

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