Determination of Reaction Order with Respect to Crystal Violet Dye

Purpose: To determine the reaction order with respect to crystal violet dye.

Procedure:

Turn on a Spectronic 20 and warm it up for at least 15 minutes. Be sure the wavelength is set to 540nm. When the instrument has warmed up, use a clean small test tube from the drawer filled 2/3 with the first NaOH solution that is planned to use, as a blank set 0% and 100% transmittance.

Take a %T reading every minute for at least 15 minutes so it may be convenient to wait until the room clock’s second hand approaches 12 before beginning the following procedure. Add one single drop of the crystal violet dye solution, invert to mix the contents of the test tube, and carefully place the tube into the instrument. When the drop hits the surface is your “time zero”, and one minute later you will begin taking readings of %T. Leave the sample tube in the instrument throughout the data collection process. Obtain readings of %T every minute for at least 15 minutes. Record %T values to one decimal place, as this allows you to convert to absorbance and retain three significant figures.

When the 15th and final reading has been taken, remove the sample from the instrument and prepare to re-zero the instrument