Basic Chemistry/Physical changes

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Physical changes don't change the particles themselves - only their arrangement or their energy.

Changes of state[edit]

This is changing from one state of matter to another.

Gas pressure[edit]

Gas pressure is due to particles hitting a surface.

  • When you increase the temperature, it makes particles move faster. This has two effects:
    • The particles hit the surfaces harder, and
    • more often.
  • This increases the pressure.
  • When you reduce the volume of the container in which the gas is contained, the pressures also increases. This is because the particles become more squashed up in a smaller space, so they hit the surfaces more often.


Diffusion is particles spreading out. Also, Diffusion is the movement of particles from a lower point of concentration to a higher point of concentration

NOTE: temperature is a major determinant of how fast a particle diffuse. Particles in a solid state don't diffuse

  • It's typically slow, for example a smell spreading slowly across a room.
  • The smell particles move away from where there are lots of them towards areas where there's only a few of them.
  • It's slow because there are also lots of air particles getting in the way of the smell particles.