Aim:
The intent of this lab is to show that there is a additive relationship between the figure of molecules that can absorb light nowadays in a solution and the sum of light absorbed by a solution. This lab should turn out that Beer’s jurisprudence and the equation A=a x B x c. is a additive relationship. Procedure:

The lone divergences in the lab process was that the stock solution was made before reaching to the lab with 0. 570 g of KMnO4 in 0. 500 L. The diluted solutions and the Spec 20 were used as directed in the lab manual. The same cuvette was used each clip to extinguish mistake. Cuvettes are all made otherwise and have a difference in how they measure. If a new cuvette was used each clip. the information would be somewhat off due to the possibility of each cuvette holding different features which affect the measurings in the Spec 20. Datas Calculations:

To happen the molar concentration of the stock solution:
*Note: Molarity is moles/ Liters so in the equation below the first half is happening the figure of moles of KMnO4 and the 2nd half is spliting the moles by the litres of the solution. Grams of KMnO4 x ( 1 mole / molar mass ( 158. 04g ) ) / Liters of stock solution = molar concentration of Stock Solution 0. 570g KMnO4 x ( 1 mole / 158. 04g ) / 0. 500 Liters = 0. 00721 Meter

To happen the molar concentration of solution # 1:
*Note: To happen the molar concentration of the first solution. utilize the molar concentration found for the stock solution. Since 5. 00 milliliter of the stock solution was used to do solution 1. multiply the molar concentration of the stock solution by 5. 00 milliliter to acquire the moles of solution 1. Once the moles of solution 1 have been found. split that by the litres of H2O that were added to solution 1. The 0. 10000 L comes from the 100 milliliter volumetric flask the solution was made in. milliliter of stock solution x ( moles of stock solution / litre ) / entire litres of solution 1 ( volumetric flask ) = M of solution 1 5. 00 mL stock solution x ( 0. 00721 moles / 1000mL ) / 0. 10000 L = 0. 000361 Meter

To happen the molar concentration of solution 2:
*Note: To happen the molar concentration of solution 2. follow the same stairss for solution 1 except usage 2. 00 mL alternatively of 5. 00 milliliter. The same stairss are used due to solution 2 being diluted from the stock solution. milliliter of stock solution x ( moles of stock solution / litre ) / entire Liters in solution 2 ( Volumetric flask ) = M of solution 2 2. 00 mL stock solution x ( 0. 00721 moles / 1000 milliliter ) / 0. 10000L = 0. 000144 Meter

To happen the molar concentration of solution 3:
*Note: To happen the molar concentration of the 3rd solution the same process is followed as happening the molar concentration of the first solution. except you will be utilizing the molar concentration of the first solution since solution three was made utilizing the first solution. milliliter of solution 1 ten ( moles of solution 1 / 1 L ) /total litres in solution 3 ( volumetric flask ) =M of solution 3 50. 00mL solution 1 ten ( 0. 00721 moles / 1000 milliliter ) / 0. 10000 = 0. 000181 Meter

To happen the molar concentration of solution 4:
*Note: to happen the molar concentration of the 4th solution follow the stairss for happening the molar concentration of the 3rd solution except usage the molar concentration of solution 2 since solution 4 was made with 50. 00 milliliter of solution 2. milliliter of solution 2 ten ( moles of solution 2 / 1 L ) /total litres in solution 4 ( volumetric flask ) = M of solution 4 50. 00 mL solution 2 ten ( 0. 000144 moles / 1000 milliliter ) / 0. 10000 L = 0. 000072 M Table 1. The molar concentration. optical density values. per centum transmission. mean optical density and transmission values are shown in the tabular array below. Solution #

Molar Concentration
Test
Optical density
% T
Average Optical density
Average % Thymine
1
0. 00003605 Meter
1
0. 821
15. 1
0. 814
15. 3

2
0. 811
15. 4

3
0. 811
15. 5

2
0. 0001442 Meter
1
0. 324
47. 4
0. 325
47. 3

2
0. 326
47. 2

3
0. 324
47. 4

3
0. 0001805 Meter
1
0. 388
40. 9
0. 402
39. 6

2
0. 406
39. 2

3
0. 413
38. 7

4
0. 000072 Meter
1
0. 208
62
0. 209
61. 8

2
0. 208
61. 9

3
0. 211
61. 5

Figure 1. The figure below shows the optical density vs. the molar concentration of KMnO4.

To happen the extinction coefficient:
The extinction coefficient is found by A/bc = a. A/c is the incline of the line from figure 1. 3139. 9/ ( mol/L ) x 1. 00 centimeter =a
a= 3139. 9 L * mol-1 * cm-1
Discussion and Decision:
In this lab the equation of Beer’s jurisprudence was proven to hold a additive relationship. The intent was to demo that molar concentration and optical density are relative to each other. This was proved through thining solutions and utilizing a spec 20 to find the optical density values. The solutions were diluted to give different molar concentrations and each concentration was placed in the spec 20. After making a spread secret plan it was obvious to see as the molar concentration increases the optical density additions. This is because there are more atoms present at higher molar concentrations and hence more visible radiation will be absorbed by the atoms nowadays.

There were many possible beginnings of mistake in this experiment. First. if one solution was diluted falsely all of the undermentioned solutions were diluted falsely since they came from the first falsely diluted solution. One of the solutions in the experiment could hold been diluted incorrect. doing all of the solutions to hold wrong dilutions and the deliberate values. particularly the extinction coefficient. to hold wrong values. Another beginning of mistake is that when thining the solutions non all of the solution transportations were done precisely due to some of the solution being transferred was frequently left in the pipet.

The bead left in the pipet after the transportation could do a difference in the existent molar concentration of each solution. The last beginning of mistake occurs from non puting the cuvette in the spec 20 at the same orientation. Although the same cuvette was used each test. some sloppiness may hold resulted in the cuvette non being placed in the same orientation each clip. Because the sides of the cuvette may be different the readings from the spec 20 may be off. The decision of the lab is that Beer’s Law equation is so additive. and the optical density is relative to the molar concentration. If this lab were preformed once more the stock solution should be placed in the spec 20 machine and the optical density should besides be found. The measurings from the stock solution could hold provided even more grounds to the decision. Overall though the lab was really successful in finding the relationship of the equation in Beer’s Law.

Questions:
2. A larger cuvette diameter will bring forth a higher optical density value. The diameter of the cuvette is the way length. or b. in the equation A = a ten B x c. The larger the way length. the higher the optical density will be because you are multiplying a and degree Celsius by a higher value. Besides there is more atoms present in a larger way length to absorb visible radiation. 3. To happen the extinction coefficient the equation A/cb= a is used. A larger cuvette diameter. or path length. would ensue in a smaller extinction coefficient. The larger the figure is on the underside the smaller the value of the extinction coefficient. 4. Solution 4 likely has the greatest mistake because it was the last solution to be diluted. Any mistakes made in thining a solution will transport through to the last solution diluted because the first solutions are used to thin the latter solutions. For illustration if solution 1 is falsely diluted so solution 3 will be falsely diluted and so solution 4 will be falsely diluted.