Changing the concentration of the reactants
3 marks · EasyThe table gives the results from an experiment measuring the rate of a reaction at two different concentrations of sulfuric acid.
| Concentration of acid (mol/dm³) | Rate of reaction (g/s) |
|---|---|
| 0.60 | 0.008 |
| 1.20 | 0.016 |
Describe the effect of doubling the concentration on the rate of reaction.
Explain why doubling the concentration causes this effect, in terms of particle collisions.
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(b) The rate of reaction doubles.
(c) Doubling the concentration increases the number of particles in a given volume, so particles collide more frequently, resulting in more successful collisions per second and a faster reaction.
Common mistakes: Not relating explanation to collision frequency.
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Marking points
B1 (b) · 1 mark · States the rate of reaction doubles when concentration doubles.
B2 (c) · 1 mark · Mentions more particles per volume or increased collision frequency.
B3 (c) · 1 mark · Links increased collisions to more successful collisions per second OR faster reaction.
Worked solution
b) Doubling the concentration doubles the rate of reaction. c) This is because there are more acid particles in the same volume, so particles collide more frequently. This leads to more successful collisions per second and an increased rate of reaction.