The reaction for luminol is basically luminol and hydrogen peroxide. In the instructions for the preparation of the chemicals, I found that the hydrogen peroxide is 44 times more concentrated than the luminol. The fact that there are two reactants, should make you wonder if the reaction is second order overall. However, in class, we presented data that showed that the natural log of the amount of light change over time was a straight line with a negative slope. This would tend to make you think that the reaction is first order, given the information here, you can confidently say that this reaction is: A. zeroth order
B. first order
C. pseudo first order
D. second order
E. third order

pseudo first order

Explanation:

We know that for a first order reaction, the plot of the natural log of the amount of reactant against time is a straight line with a negative slope. In this case the amount of substance is monitored using the amount of light change. Hence, the plot of the natural log of the amount of light change against time was a straight line with a negative slope.

The statement above characterizes a first order reaction. However, we must remember that the reaction is bimolecular; it involves luminol and hydrogen peroxide. The hydrogen peroxide is 44 times more concentrated than the luminol making the reaction a pseudo first order reaction.

A Pseudo first-order reaction can be defined as a second-order or bimolecular reaction that is made to behave like a first-order reaction(Byjus).