Concentration data can be used to determine reaction order.

If the rate law for a reaction is known to be of the form where n is either zero, one or two, the order of the recation can be determined graphically.

Experimentally Determined Data

The following data were collected foror a hypothetical reaction whose rate is known to only depend on the concentration of a single reactant, A. The order of the rate law with respect to A is unknown. 

                   
Time (s)            [A](M)
---------------------------------
  0                 1.00
  5                 0.82
 10                 0.67
 15                 0.55
 20                 0.45
 40                 0.20
 60                 0.09
This data can be used to determine the order of the reaction. We assume that the reactions is either zeroth, first or second order.

Is the reaction 0th order?

If the reaction is 0th order, a plot of concentration versus time will result in a straight line. Since this plot is clearly non-linear, the reaction is not 0th order.

Is the reaction 1st order?

If the reaction is 1st order, a plot of the natural log of concentration versus time will result in a straight line. Since this plot is clearly linear, the reaction is 1st order.

Is the reaction 2nd order?

If the reaction is 2nd order, a plot of one over concentration versus time will result in a straight line. Since this plot is also clearly non-linear, the reaction is not 2nd order.

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