Driving Question: How can you determine the concentration of a colorful solution?

Introduction & Background:

The purpose of this lab is to determine the concentration of a colorful solution.  To determine the concentration of a colorful solution, five solution of Copper (II) Sulfate of different concentrations are prepared.  A Colorimeter is used to measure the absorbance of the five solutions, and a calibration curve will be constructed using the measurements.  Based on the calibration curve, and the absorbance of a CuSO4 solution with unknown concentration, the concentration of that solution can be determined.

When light interacts with light-absorbing particles, some of the light is removed.  The ability to absorb color, as well as what color is to be absorbed, depends on the type of particle present.  When comparing two solutions of the same color substance with different concentrations, the solution with the higher concentration appears darker.  The higher concentration appears darker because it has more absorbing particles and it absorbs more of the incident light.