Background and Identification
A colorimeter is a device that measures the “absorbance of particular wavelengths of light by a specific solution.” (Wikipedia) This means that when a particular color of light or wavelength is directed through a chemical solution, then some of the light is transmitted and some of it is absorbed. You can use it to determine the concentration of an unknown substance by comparing the absorbance of a solution of known concentration and compare it with the absorbance of a solution with an unknown concentration.
In a lab setting a chemist may use the colorimeter to determine colors or determine the concentration of a substance in solution. One might use a colorimeter in lab research, water quality analysis, or keeping track of the hemoglobin content in blood.