Is The Rate Law Determine The Reaction Order?

The reaction order, based on the rate law, was first order with respect to crystal violet and second order with respect to OH-. The rate law was as follows: Rate law = k [CV]1[OH-]1 where k equaled 2.61. In order to determine the reaction order with respect to crystal violet, the graph that described the relationship between ln[CV] and time (seconds) was Figure 2. Not only did Figure 2 generate a more linear relationship, but it had the highest R2 value of 0.992 than ([CV] versus time) and ([1/CV] versus time) (see Figures 1, 2, and 3). The closer the R2 value is to 1, the closer the data fit the regression line, which in this case was Figure 2. With respect to crystal violet, the overall reaction order was that of first order. This data allowed for the analysis of how the [CV] changed for each different OH- concentrations.
By taking the natural log of crystal violet and plotting it versus time, it can be seen how the R2 values fluctuate (see Figure 4).
Because the R2 values varied, so did the Kobs per concentration (see Table I). Within the author’s case, two graphs were plotted as one point was further out on the graph (see Figure 5). With Figure 5, the first three points were more aligned and showed a linear relationship, while the last point, which corresponded to 0.0262 M NaOH served as an outlier. The author decided to take out the last point and generated a new graph (see Figure 6), which generated a more linear graph and resulted in a higher R2 of 0.9892. This caused a debate between what the reaction order was with respect to OH- as Figure 5 had a slope closer to 1, while Figure 6 had a slope closer to 2 (see Figures 5 and 6). Since the data point in Figure 5 was an outlier, this suggested error (the solution was shaken too many times; crystal violet was a really dark purple) as the first three data points formed a linear relationship. Therefore, based on the R2 value, Figure 6 was used to determine the reaction order with respect to OH-; second
order.

In terms of error, for Figures 1-3, the solution was placed too early into the colorimeter as the solution was inverted more than twice and it was a dark purple for all of the different NaOH concentrations. This could have caused the colorimeter to not collect data correctly as minimal light was present. This could have affected how much light was absorbed through time and how fast the reaction took place depending on the NaOH concentrations. Therefore, this would then, in turn, affect the Kobs at various concentrations, which would then affect the order of the reaction with respect to OH-. Overall, the rate law informs the researcher about the reaction rate in relation to the concentrations of the reactants.
Because the overall reaction order is third, the three particles will not bounce off of each other at the same precise moment; this demonstrates the mechanism of unimolecularly with crystal violet. Crystal violet undergoes an internal rearrangement to become CV+* before it can react with two OH- molecules, which is a slow process.

After analyzing these data, it can be concluded that the reaction rate increases as the concentration of NaOH increases.