Concentration And Absorbance In Beer-Lambert Law

Figure 1 shows the relationship between concentration and absorbance known as the Beer-Lambert law or calibration curve. The data from the made solutions in table 2 was used to create the graph. The graph has a linear trend line that predicts where a point would fall on the graph. The equation of the trend line is equation 7: y=0.9508x-0.0055 with a R2 value of 0.99943. This equation was used to find the true concentration of the made solutions as well as the unknown solution. The R2 value indicated that the trend line fits the data very well because the value is close to one.
Discussion: Table 1 is an abbreviated version of the data used to create the desired molarity of the measured solutions of copper (II) sulfate. Equation 5 was used to …show more content…
Equation 1 was used to find the T value, Equation 7 was used to find the concentration, Equation 2 was used to find the absorbance value of the standard and unknown solutions while equation 3 was used to find the absorbance of the made solutions. When comparing the absorbance of the made verses the standard solutions, the values looked very similar. However, after using Equation 6 to find percent error of the concentration and absorbance, it was clear that there was a large amount of error in the experiment. The 0.500M and 0.050M solutions did not have a large percent error compared to the percent error for the 0.100M and 0.200M solutions. The errors in these solutions must have canceled out which would explain why the last solution, 0.500M, did not have a large percent error. Figure 1 was created to prove the Beer-Lambert Law by showing the linear relationship between concentration and absorbance of colored solutions. Since the R2 value is so close to one, it can be concluded that the relationship is valid. The chart is essential to the lab because the concentration of the unknown and the made CuSO4 solutions cannot be found without the equation that was derived from the linear trend