Chemical Kinetics

In this experiment you will find the rate law and rate constant of a chemical reaction.

Experimental Procedure

Part 1: Beer-Lambert's Law Validation

In this section you will validate Beer-Lambert's law and calculate the molar absorption coefficient of the iodide ion at several wavelengths.

  1. Prepare solutions of iodide at a number of different concentrations. You will recieve an Iodine stock solution at a concentration of 0.05 M.
  2. Obtain the absorption spectrum for each concentration.
  3. Choose several wavelengths within the range of iodide absorption.
  4. Plot the absorption at these wavelengths as a function of the concentration. Is the obtained plot linear? If not, is there a regime where the plot is linear?
  5. Calculate the molar absorption coefficient of the iodide at each selected wavelength.

Part 2: Determination of Optimal Acid:Acetone:Iodide Ratio

Find the ratio of acid to acetone to iodide that will produce a reaction time of 2-3 minutes within the experimental framework. You will recieve a concentrated HCl solution at 32% (w/w) and a 100% w/w solution of acetone.

Part 3: Finding the Reaction Order for Each Component

  1. Measure the absorption as a function of time. Plot the iodine concentration versus time and determine the reaction rate of the iodination.
  2. Repeat the previous step with different concentrations of acid, acetone and iodide. Note: take at least 4 points per component.
  3. Calculate the reaction order for each component.

Part 4: Data Analysis

Using the data from the previous section, calculate the rate constant for the reaction.