In this experiment, you will use a Colorimeter or Spectrometer to determine the amount of free chlorine
in a sample of swimming pool or hot tub water.
The solution used in this experiment has a red color, so Colorimeter users will be instructed to use the 565 nm (green) LED. Spectrometer users will determine an appropriate wavelength based on the absorbance spectrum of the solution. You will first measure the absorbance of light by aqueous solutions of known chlorine concentration. From the resulting graph of absorbance vs. free chlorine concentration (Beer’s law), you will be able to determine the free chlorine content of your swimming pool sample.