Changing the pressure

2 marks · Normal

For equilibria involving only solids and liquids, changing the pressure has very little effect. Give two reasons why.

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Solids and liquids are not compressible so their concentration is not changed significantly by pressure. Their particles are already close together, so increasing or decreasing pressure has almost no effect.

Also accept: Particles in solids/liquids are very close together; No significant change in concentration or volume

Common mistakes: Saying solids and liquids are not affected without giving a reason

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Marking points

B1 · 1 mark · States solids and liquids are incompressible (or their volume or concentration does not change).

B2 · 1 mark · States that their particles are already close together or that changing pressure does not significantly change their state.

Worked solution

1. Solids and liquids are incompressible; changing pressure does not change their volume. 2. Their concentration remains the same, as their particles are already packed closely together.