Rates of reaction - kinetics
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Can you explain why the reciprocal of time, 1/t can be used to express the rate constant in the Arrhenius equation.
Ulex says
This mathematical device can only be used in conjunction with the initial rate method of studying rates of reaction. The time, t, is the time it takes for a certain amount of reactant to be used up (or a certain amount of product to be formed). So therefore
Rate of reaction = amount of reactant used / t
But the amount of reactant used is the same for each run of the experiment and is therefore constant so
Rate of reaction = constant x 1/t
Which means that the reciprocal of time may be used as a comparative measure of the rate.
When you are doing a series of experiments at different temperatures to find the activation energy, the only variable is the temperature. The concentrations of the reactants are kept constant. If the rate equation is written as
Rate of reaction = k[A]a[B]b ….etc
And if [A], [B] etc are constant then
k is proportional to rate of reaction and therefore k is proportional to 1/t.
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updated: 03 March 2006
