Diffusion in gases
2 marks · NormalA scent is sprayed at one end of a classroom. After a short time, the scent can be detected throughout the room.
Explain why the scent spreads through the room, using the particle model.
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Also accept: Gas particles move randomly and spread from high concentration to low concentration until evenly mixed.
Common mistakes: Not referring to particles.; Not mentioning random movement.
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Marking points
M1 · 1 mark · Mentions that gas particles move randomly.
M2 · 1 mark · States that the scent spreads from a region of high concentration to a region of low concentration.
Worked solution
The scent spreads because the gas particles move randomly and spread out from where they are more concentrated to areas where they are less concentrated, until the scent is evenly distributed throughout the room.