Whether a reaction is of first order or not can be verified by using the analytical methods based on the rate equations. The reagents are allowed to react, the change of concentration is measured at different time intervals. For a first order reaction:
(i) Plot of log [A0]/[A] versus t gives a straight line passing through the origin.
(ii) Plot of log[A] versus t gives a straight line with an intercept log [A]0 and a slope = – k /2.303.
(iii) Plot of [A] versus t is exponential.
(iv) The value of k calculated by using kt = 2.303 log [A]0 / [A] for different time intervals come out to
be same.
(v) The half life period is independent of the initial concentration of the reactant.