Taking the natural logarithm of Arrhenius equation yields:
Rearranging yields:
This has the same form as an equation for a straight line:
where x is the reciprocal of T.
So, when a reaction has a rate constant that obeys the Arrhenius equation, a plot of ln k versus T gives a straight line, whose gradient and intercept can be used to determine E and A. This procedure has become so common in experimental chemical kinetics that practitioners have taken to using it to define the activation energy for a reaction. That is, the activation energy is defined to be (−R) times the slope of a plot of ln k vs. (1/T):