# Rate Law Determination Of a Crystal Violet Reactio

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Abstract: In this lab, the purpose was to determine the reaction rate for the absorption (concentration) of the reaction. The components needed for the rate law in this lab are the k value as well as determining if the reaction is zero, first, or second order. The graphical method will be used to determine the order as well as the “K” value. The absorption of the green light increased over time as the reaction occurred. Background: A reaction rate is the decrease in concentration of a reactant or the increase in concentration of a product with time. Thus, the units for the reaction rate are usually Molarity per second (M/s) – that is , the change in concentration (measured in molarity) divided by a time interval (seconds in this case) (Chemistry: The Central Science, P. 527). Rate is usually calculated by taking an average of the disappearance or appearance of a compound with respect to time. In this case it is calculated by the absorbance of the light. Reaction rate is affected by any catalysts present (which speed up the reaction usually with an intermediate step), temperature (increases the number of particles collisions), concentration (increases the number of collisions), and surface area (increases the space available for collisions). Reactions can only occur when collisions take place. The most generic form of the rate law is Rate = K * [A]m * [B]n where (k is a constant specific to an equation and temperature). Now, the compounds A and B might not have any effect on the rate, which would cause them to drop out of the equation completely, or they might have so much effect that they are raised an order (squaring the concentration). The rate law for this reaction is k [CV+]m[OH-]n. Since the hydroxide ion concentration at the beginning is about 1000 times larger than the concentration of crystal violet, [OH-] will not change that much during this