For a series of solutions that were prepared in lab, you measure absorbances of
ID: 890013 • Letter: F
Question
For a series of solutions that were prepared in lab, you measure absorbances of 1.1, 0.81, 0.54, and 0.27. When you plot absorbance versus concentrations you find a linear trend and the equation of the best-fit line is y=0.0724x + 0.0007. What is the average molar absorptivity of your sample? Given the calibration curve you created above, you take the absorbance of your samples at the same wavelength and in the same cuvette and find a value of 2.8. What do you do to find the true concentration of the sample?
Explanation / Answer
We know according to Beer-Lambert's law,
A = ebc
where,
A is absorbance
b = path length
e = molar absorptivity
a plot of A vs c gives a straight line with slope = eb
from the above plot we have,
slope = 0.0724 = eb
Assuming the path length is 1 cm
the average molar absorptivity = 0.0724
An absorbance od 2.8
Using Beer's law,
A = ebc
c = A/eb = 2.8/0.0724 x 1 = 38.67 would be the concentration of sample
[note: If path length differs, this value would change accordingly]
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.