The absorbance values At & A0 recorded in the experiment 'Rate Law Determination of the Crystal Violet Reaction' are used in the place of the concentration values of which species

A. CVOH
B. CV+
C. –OH
D. Na+
E. H2O

We don't know what experiment you are doing nor how you are doing it. My guess wouldn't help much.

The answer is CV+

In the experiment "Rate Law Determination of the Crystal Violet Reaction," the absorbance values At and A0 are used in the place of the concentration values of the species CV+ (Crystal Violet cation) because absorbance is directly proportional to the concentration of a substance in solution according to the Lambert-Beer Law.

The Lambert-Beer Law states that the absorbance of a sample is directly proportional to the concentration of the absorbing species and the path length of the sample cell. In this case, the species involved in the reaction is CV+, which undergoes a reaction that leads to a change in its concentration over time.

By measuring the absorbance of the solution at different time intervals (At) and at the initial time (A0), we can indirectly determine the concentration of CV+ at each time interval. The change in absorbance over time is related to the rate of the reaction, providing valuable information for determining the rate law of the reaction.

Therefore, in this experiment, the absorbance values (At and A0) are used as a substitute for the concentration values of the species CV+ in order to study the kinetics of the Crystal Violet reaction.