This reaction is as below in a simplified form by abbreviating the crystal violets chemical formula as CV.
The violet-colored CV+ reactant slowly faded to a colorless product as the reaction proceeded, following the typical behavior of any indicator. The colour change were be measured by a Vernier Colorimeter set at 565 nm of wavelength in assumption that absorbance is directly proportional to the concentration of crystal violet according to Beer’s law.
The molar concentration of the sodium hydroxide, NaOH, solution was much greater than that of crystal violet. This ensured that the reaction, which is first order with respect to crystal violet, was first order overall throughout the practical experiment. The reactions were monitored at different temperatures, while maintaining the initial concentrations of the reactants the same for each of the trial. The effects of temperature change on the rate of reaction were observed and measured. Finally, the activation energy, Ea, for the reaction was calculated.
In this lab Experiment the apparatus and materials used included Lab Quest , Lab Quest App Temperature Probe, Vernier Colorimeter, Temperature Probe, 5 plastic cuvettes, 0.10 M sodium hydroxide, NaOH, solution, 2.5 × 10–5 M crystal violet solution, 1 liter beaker, ice, watch with a second hand, two 10 mL graduated cylinders, two 100 mL beakers and 50 mL beaker.
In this experiment, the procedure was as follow. The initial step involved obtaining and wearing goggles. This was followed by connecting the Colorimeter to Channel 1 of LabQuest and the Temperature Probe to Channel 2 of LabQuest and choosing New from the File menu.
The next step involved changing the data-collection rate to 1 samples /second and the length to 200 seconds. The colorimeter was the calibrated and the calibration used for all the four trials in the done in the experiment.