Beer's Law

Beer’s Law

Data: Wavelength: 810 nm
Table 1
Sample # mL of stock placed in the 100 mL flask
Initial buret
(mL)

Final buret
(mL)
Actual mL used
(mL)
Calculated concentration
(M)
% T
(%)
Absorbance
1
1
1.19
2.19
1.00
.01
78.6
.105
2
2
.31
2.29
1.98
.0198
61.1
.214
3
3
2.29
5.31
3.02
.0302
46.2
.335
4
4
5.31
9.30
3.99
.0399
36.1
.442
5
5
9.30
14.31
5.01
.0501
27.6
.559
6
6
14.31
20.32
6.01
.0601
21.4
.670
7
7
20.32
27.28
6.98
.0706
16.5
.783
8
8
27.38
35.32
7.94
.0794
12.9
.889
9
9
.29
9.30
9.01
.0901
9.9
1.00
10
12
9.30
21.29
11.99
.1199
4.6
1.337
11
15
21.29
36.31
15.02
.1502
2.0
1.699
12
18
.25
18.31
18.06
.1806
.9
2.046
13
20
.23
20.21
19.98
.1998
.5
2.301
14
--
--
--
--
.30 M-pre-made
.1
3.00
15
--
--
--
--
.50 M-pre-made
.1
3.00
16
--
--
--
--
.75 M-pre-made
.1
3.00

Table 2
Wavelength (nm)
Epsilon
810
11.708
800
11.707
790
10.435
780
11.308
770
11.211
760
10.68

Calculations: Calculating Concentration: M1M2 = M2V2 (100)(1.00) / (100) = 0.01 M Calculating Absorbance: Absorbance = -log T T = %T / 100 Absorbance = -log (.786) = .105 % Tabulated Results: shown in Table 1
Graphs:
Absorbance vs. Concentration: Page 4 Absorbance vs. Wavelength: Page 5 Epsilon vs. Wavelength: Page 6
Color wheel: Page 7

Discussion: The wavelength that my group investigated was 810 nm. The equation for the best-fit line that was drawn for my data came out to be y = 11.211x – 0.0056. The value of Epsilon that corresponded to my data was 11.708. The sixteen points that correlates to my data all seem to rise pretty steadily as the concentration increases expect for the three pre-made solutions which seem to flatten out at an absorbance reading of three. Points one through eleven are on the line of best fit. Points twelve and