Kinetics of a Redox Reaction - AP Chemistry Classic Laboratory Kit

By: The Flinn Staff


Classic AP Requirement #12b—Determination of the Rate of a Reaction and Its Order

In this technology-based lab, students study the rate of the reaction of FD&C Red Dye #3 with sodium hypochlorite. The color change occurring in this oxidation–reduction reaction is followed using a spectrophotometer to quantitatively measure the rate of disappearance of the colored reagent. First, students create a calibration curve for the dye. Then they find the order of reaction for each of the reactants by varying the concentration of each reactant individually. Finally, a graphical analysis of the relationship of concentration versus time is used to calculate the rate constant.

This lab challenges the students’ understanding of the relationships of concentration, reaction rate, and the rate law. Includes optional FD&C Blue Dye #1 for better absorbance with some colorimeters. Two 50-minute periods are required to carry out this experiment—suggested breaking point is given in the Teacher Notes. A spectrophotometer or colorimeter is required.

Complete for 30 students working in pairs.

Materials Supplied:
FD&C Red No. 3
FD&C Blue No. 1
Sodium hypochlorite solution
Syringes, 3-mL
Syringes, 12-mL