12-A-1
Rates of Reaction: Iodination of Acetone
Introduction:
The rate at which a chemical reaction occurs depends on several factors: the nature of the
reaction, the concentrations of the reactants, the temperature, and the presence of possible
catalysts. In this experiment you will study the kinetics of the reaction between iodine
and acetone in acid solution:
For this reaction, you will determine the order of the reaction with respect to acetone and
HCl and find a value for the rate constant, k. Since the concentrations of acetone and
HCl are much higher than that of I2, the concentrations of acetone and HCl will change
very little. Thus the rate will be determined by the time needed for iodine to be used up.
Iodine has color so you can easily follow changes in iodine concentration visually. The
equation, rate = k(A)m(H+)n(I2)p, can be simplified to rate = k[I2]/t since the values for
acetone and HCl essentially remain constant during the course of any run.
Purpose:
The purpose of this reaction is to determine the orders for the reactants, the rate
expression, and the rate constant for the reaction between iodine and acetone.
Equipment/Materials:
4.0 M acetone solution 125 mL Erlenmeyer flasks
1.0 M HCl solution 10 mL graduated cylinders
0.0050 M iodine solution watch or other timing device
100 mL beakers watch glass covers for beakers
Safety:
• Always wear an apron and goggles in the lab
• Acetone is flammable. There should be no open flames in the room.
