Changing the surface area of the reactants
2 marks · EasyExplain why a reaction between a solid and a liquid is faster when the solid is ground into a fine powder rather than used as one large lump.
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Powdering increases the surface area exposed, allowing more particles to collide with the liquid per second, which increases the chance of successful collisions and makes the reaction faster.
Common mistakes: Just 'it is faster' without explanation
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Marking points
M1 · 1 mark · Mentions increased surface area from powdering.
M2 · 1 mark · Correctly explains how this leads to more particles being available for collisions, increasing reaction rate.
Worked solution
Fine powder increases surface area.
More particles can collide with the liquid per second, making the reaction faster.