Beer's law lab

Beer's law states that the more concentrated a solution is, the darker it will appear because of the presence of more of the solute.

Purpose- Determine concentration of solutions based upon how dark the solutions are.
Materials- Nickel Nitrate, clear (clean) test tubes, pipets, distilled water, colorimeter (yes, that's its name), cuvettes and a computer to record data.
Procedure-
Create control for experiment by filling one cuvette with only distilled water and entering in the data from the colorimeter to the computer. Then, switch the colorimeter's settings to red light (as we're dealing with a green-colored solution). Next, add in different ratios of Nickel Nitrate to distilled water in different test tubes, but only so that the result is a total of 10mL of mixture (Ex: 2mL of Nickel Nitrate to 8mL of water, 4mL of Nickel Nitrate to 6mL of water and so on). Stir all test tubes full of the different concentrations of Nickel Nitrate so they are all properly mixed with the distilled water in the test tubes. Enter in all data from colorimeter to computer by pouring one cuvette with one of each of the different of mixtures created so there is one cuvette for each different mixture ratio. The data entered should have  aslightly linear pattern, although we experienced one outlier in our data. In the case of an outlier, it is advised to draw a line of best fit into the graph to determine an estimated trend of concentration. Then, we were given 3 unknown mixtures that were prepared before the experiment and needed to apply our knowledge and data to determine the concentration and absorbance of each of them.
Absorbance for the 3 unknowns were:
1- .186
2- .551
3- .367
Concentration (in moles) were:
1- .155 M
2- .365 M
3- .26 M
Conclusion: Unknown mixtures' concentrations can be determined by the data recieved from known solutions and comparing their absorbance with the unknowns'. Thus, Beer's law is a reliable basis for this sort of experiment.