In the reaction of CV with NaOH, the order of CV is 1 (first order). However, in an experiment that I did with a colorimeter, I did not entirely come up with this value. Graphical analysis was done to determine the best wavelength from the absorption spectrum and lambda_max = 590 nm. After looking at the absorbance readings (or manipulations of A in relation to each order) vs. time at 0 order through 2nd order at 590 nm, it was concluded that 0 order (A vs t) gave the best line; this does not match the true value. On the other hand, at 526 nm, which had a lower absorbance level than 590 nm, absorbance readings (and its manifestations) vs. time had the best line at first order (ln A vs t) than 0 and 2nd orders. Exactly why is the true value (first order) available at 526 nm but not at the lambda_max 590 nm?