Lab report-Beer Law PDF

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Beers law...

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ABSTRACT In this lab, we measured the amount of absorbance from 5 different solutions and then found the concentration by using a colorimeter and then comparing the transmittance and absorbance. The concentration of Allura red was 2.843x10^-6 M. INTRODUCTION The purpose of this experiment was to find the concentration of Allura red in Gatorade by making five different solutions. We used the equation M1*V1=M2*V2 to make the solutions. We were given the M2 and V2 and also the M1 so all we needed to solve for was V1, this would give us our range. After finding the calculations we transferred some of the solutions into the cuvette to find absorbance. A graph was made using the data we got from the colorimeter and the relationship between absorbance and concentration was determined. This relationship is known as Beer’s law which states  that the absorptive capacity of a dissolved substance is directly proportional to its concentration in a solution. We put these calculations into the computer program and received a calibration curve which is a general method for determining the concentration of a substance in an unknown sample by comparing the unknown solution to a set of standard samples of known concentration. DATA What mL of Dilution factors Table 1: Concentration vs. Absorbance Solutions

Dilution factors in ¾ cuvettes

Concentration (mol/L)

Absorbance

1

4mL

0.00008

0.133

2

5mL

0.00001

0.159

3

6mL

0.000012

0.192

4

7mL

0.000014

0.240

5

8mL

0.000016

0.286

RESULTS y=2.843x10^-6 M Absorbance = m*x + b m = 2.159x10^.004 x – concentration of Allura Red b = -0.06138

The absorbance of the red Gatorade was 2.843x10^-6 M. So,  the concentration of Allura Red is: x = (Absorbance – b) / m = 2.843x10^-6 M. The concentration of Allura Red in red Gatorade is: 2.843x10^-6 M. which was given by the calibration curve.

Graph 1: Absorbance vs Concentration

M1V1=M2V2 0.0001*V1=50mL*6E-6 V1= 3 mL 0.0001*V1=50mL*2E-5 V1= 10mL This formula gives us the range of Gatorade we can use in the five solutions

DISCUSSION In this experiment, we were tasked with finding the concentration of Allura red in Gatorade. To be able to determine this we had to make a total of five solutions using the given information in the manual ( M1V1=M2V2). The absorbance of red Gatorade was determined, simply by putting it into the equation, the concentration of Allura Red was calculated. In this specific lab, we had to be very specific with the measurements so some possible reasons why there could have been errors would be because of miscalculations or by doing the math wrong. The colorimeter was set to 470 nm to more accurately predict the correct concentration. Further Questions: 1) Concentration of Allura Red: 0.0001 mol/mL M = 0.0001 mol/mL V = 20 oz = 0.591 L = 591 mL n = 0.0001 mol/mL * 591 mL = 0.0591 mL This means that there is 0.591 mL of Allura red in 20 oz of Gatorade 2) The molar mass of Allura Red: 496.42 g/mol 0.0591 mol * 496.42 g/mol = 29.34 g There are 29.34 grams of Allura Red in one 20 ounce bottle of Gatorade. The calculations are reasonable since the mass of one 20 ounces is equal to 567 grams....