top of page
Kinetics of Crystal Violet

Kinetics of Crystal Violet


This 4-wavelength Colorimeter measures the amount of light transmitted through a sample at a user-selectable wavelength in order to determine the concentration of a solution.  Features such as automatic sensor identification and one-step calibration make this sensor easy to use.  The colorimeter can be used for colored solutions and provides an alternative to the more expensive UV-Vis instrument.  Unlike the UV-Vis instrument, the colorimeter measures within the visible range of the electromagnetic spectrum.    

In this laboratory experiment, your students will use the Vernier colorimeter to determine the rate law of crystal violet and its reaction with sodium hydroxide.  Using the absorbance values, they will generate a zero, first, and second order calibration curve and compare the linear regression lines.  They will also determine the reaction order in respect to hydroxide.  Finally, they will determine the rate law for the reaction and use the ABS value to report a reaction half-life.  


    This U-PIK will include enough materials for six student groups.  Suggested group size is 2-3 students.  The U-PIK will include the following:


    • 6 colorimeters 
    • 6 LabQuest 2 interfaces
    • 7 vials of 0.01 M NaOH solution
    • 7 vials of 0.02 M NaOH solution
    • 7 vials of 0.000015 M crystal violet solution
    • Set of plastic cuvettes
    • 6 boxes of Kimwipes
    • 12 stirring rods
    • 12 100-mL beakers
    • 12 50-mL graduated cylinders
    • 6 bags of transfer pipettes

    You will be required to provide your own water (distilled or deionized) needed for the experiment.  Tap water is not recommended, however, it will have a minimal impact on the laboratory experiment.    


    The colorimeter can be easily used to support the concept of the visible spectrum.  All solutions will be colored and analyzed in the visible portion of the electromagnetic spectrum.     


    Due to the mathematical concepts presented (slope and linear regression line), the laboratory should be introduced in a high school science classroom.  It should be suitable for any science course discussing kinetics and reaction rates.  


    Time:  One laboratory period.  


    Student Level:  

    ADVANCED (Grades 11-12)

  • Colorimeter User Manual

  • Lab Experiment: Preview Document

bottom of page