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Using experimental results to determine the order of a chemical reaction and the rate constant from your understanding of chemical kinetics and species half life.

A reaction is defined by the following scheme:

X à  Y

When the concentration of X in a solution is 1.02 M, the half-life (t1/2) is 160 seconds.

When the concentration of X in solution is 2.05 M, the half-life (t1/2) is 80 seconds.

The above information applies when the reaction takes place at 25 degrees Celsius.

(a) What is the order of the reaction?
(b) Calculate the rate constant for the reaction.

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Solution Preview

Please note that the attached file contains a complete solution to the question.

PART ONE: What is the order of the reaction?
To answer this question, we will consider the equations used to calculate half-life (t1/2) for zero order, first order, and second order reactions. In each case, [X]o=concentration of X at time zero; k = rate constant.
For a zero order reaction, t1/2 = [X]o/(2k)
For a first order reaction, t1/2 = 0.693/k
For a second order reaction, t1/2 = (k*[X]o)-1
Considering the equations shown above, it is clear that for a first order reaction, the half-life is independent of the ...

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