Solutions : Beer's Law

Explore the relationship of the absorbance of light through a solution and the concentration of the solution. Use the relationship to find the concentration of a solution.

Lab Summary:

In this activity, students will make known concentrations of copper(II) nitrate solution. They will use a colorimeter to measure the absorbance of a specific color (wavelength) of light through the known concentrations in order to establish a "standard curve". They will determine the relationship of the absorbance of light to the concentration of the solution and use this relationship to estimate the concentration of an unknown solution of copper(II) nitrate.

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(student version)

Method:

Use a Colorimeter to determine the concentration of one or more unknown solutions by comparison to a standard Beer’s Law absorption plot.

Here's What You Need:

Probeware

• PASPORT Colorimeter with cuvettes (PS-2121)
• Xplorer GLX Graphing Datalogger (PS-2002)
  (or alternate PASPORT interface -- see other options)

Other Materials

• Beaker, 100-mL
• Label
• Pipette with bulb, 10 mL
• Stirring rod
• Test tube, large
• Test tube rack
• Tissue
• 0.25 M copper(II) nitrate, Cu(NO₃)₂
• Water, distilled

Lab Manual:

This activity is included in Explorations in Chemistry (PS-2808), complete with Teacher Information pages, student instructions and handouts, and sample data for a total of 25 probeware-based labs. For your convenience, we offer bundles which provide the probeware necessary for the activities in the manual. For more information on these resources and bundles, click here.