Changing the pressure on the reaction
3 marks · EasyA student wants to increase the rate of a reaction involving only liquids. She decides to increase the pressure.
Explain why this change in pressure will have little effect on the rate of reaction.
Describe how the particles in a liquid are arranged.
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(a) Increasing pressure does not affect the rate of liquid reactions because liquid particles are already very close together, so there is little change in how often they collide. · must show liquid particles already close together, little or no increase in collision frequency or concentration
(b) Particles in a liquid are closely packed but can move and slide past each other. · must show closely packed, can move/slide past each other
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Marking points
B1 (a) · 1 mark · States that liquid particles are already closely packed together or there is little room between particles.
B2 (a) · 1 mark · States that increasing pressure does not significantly increase collisions or concentration.
B3 (b) · 1 mark · Describes liquid particles as closely packed but able to move/slide past each other.
Worked solution
a) Increasing pressure has little effect because liquid particles are already very close together and there is minimal space between them, so increasing the pressure only slightly changes their arrangement and does not significantly increase the frequency of collisions.
b) In a liquid, particles are closely packed but can move and slide past each other.