Polarimeters can be used in kinetics experiments to follow the change in concentration of an optically active sample as a reaction proceeds. Sugars are common examples of optically active compounds. Sucrose is a disaccharide that can be broken down into its two substituent monosaccharides, glucose and fructose.

This process occurs too slowly in water to be monitored on any real time scale, so a catalyst, acid or enzyme, must be added to accelerate the reaction rate. In this experiment, hydrochloric acid is used to catalyze the reaction while its rate is monitored using a polarimeter. The experiment will be repeated using the enzyme invertase to catalyze the reaction.


In this experiment, you will

  • Calculate the specific rotation of sucrose using a Polarimeter.
  • Observe the cleavage kinetics of sucrose with an acid catalyst, hydrochloric acid.
  • Observe the cleavage kinetics of sucrose with an enzyme catalyst, invertase.
  • Calculate the rate constant for each run from the rotational readings.