CChieh@UWaterloo.ca

Experiment: Kinetics

Chemical Kinetics Experiements

  1. The Effect of Concentration on Reaction Rates
    --- the iodide-persulfate reaction

    In CHEM123/125 lectures on the following topics,

    Chemical kinetics
    Reaction rates and orders
    you have learned how the order of a chemical reaction can be determined, and how the rate law can be derived. In this experiment, you actually determine the order and the rate law of the reaction: (NH4)2S2O8 + 2 KI = I2 (NH4)2SO4 + K2SO4 or S2O82- + 2 I- = I2 + 2 SO42- You will learn these lab skills:

  2. The effect of temperature and catalyst on the reaction rate
    ---the iodide-persulfate reaction

    Using the same reaction, but you cary out the experiment at different temperatures to investigate the temperature effect on reaction rates. The temperature effect is best described by the activation energy,
    Ea, defined in the Arrhenius equation

    k = A e- Ea / R T Further more, you also investigate the effect of a catalyst on the reaction rate. You determine the change in activation energy when a catalyst is added.

    The Arrhenius equation is a model to correlate the rate constant k with temperature T. Many reactions follow this model, and it becomes a theory of chemical kinetics. You can apply the same technique to develop a scientific theory.

    There lab skills you have acquired from Experiment 2 comes handy for this experiment. Lots of data are collected, and you are required to carry out extensive calculations from the results. The tables layed out in the Lab manual help you organize the information, and the organization of information is an important skill.

    For the evaluation of Ea, the graphic method is suggested. Again, this is a useful technique, but modern computers may have other techniques to derive the same results. Feel free to investigate.

    cchieh@uwaterloo.ca