Rates of change (AS)
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How does pressure affect the rate of reaction?
Corrie writes ....
Pressure will have its greatest effect on reactions involving gases. If the pressure is increased (but the temperature kept constant), the gas molecules will be be closer together and collide more frequently. The increase in the frequency of collisions will increase the rate of the reaction.
Students often believe, mistakenly, that if the pressure is increased, the energy of the molecules is also increased, and therefore that this will also increase the rate of a reaction. If the temperature is kept the same, only the frequency of collisions is affected when the pressure is changed.
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updated: 17 June 2007
