DATA UNKNOWN NUMBER6 A. Wavelength of maximum absorbance, , determined from your
ID: 561837 • Letter: D
Question
DATA UNKNOWN NUMBER6 A. Wavelength of maximum absorbance, , determined from your prelaboratory graph of the data in Table 2 2 SAm B. Concentration of E C. Diluted Solution rythrosin B standard solution 8, 312x10, Absorbance 0.022 133 D. Diluted Unknown Absorbance CALCULATIONS Show caleulations in area provided on next page.) A. Known Solutions 1. Molarity of standard solution (I) 2. Molarity of stock solution (S) 3. Calibration curve values Absorbances (from Data) 8: 34) 1.148 x 10 0-03 2 0 13 :133Explanation / Answer
Prepare a plot of molarity of the standard solutions vs the absorbances as shown below.
B) The regression equation is y = 9429.3x – 0.0115 where y is the absorbance of the solution having concentration x (in M)
Put y = 0.165 (no unit) in the linear equation and obtain
0.165 = 9429.3x – 0.0115
====> 9429.3x = 0.1535
====> x = 1.6279*10-5
The concentration of the unknown diluted solution is 1.6279*10-5 M (ans).
C) Beer’s law is given as A = *C*l where is the molar absorptivity of the solution; C is the concentration of the solution and l is the path length of the solution. The path length of the solution is usually taken as 1.00 cm.
Compare this equation with the regression equation and we can identify that *l = 9249.3.
Since x has unit M, the unit for 9429.3 will be 9429.3 M-1; therefore,
*(1.00 cm) = 9429.3 M-1
====> = (9429.3 M-1)/(1.00 cm) = 9429.3 M-1cm-1 (ans).
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