Week 4 -Spectroscopic analysis of aspirin re-Lab Questions If 25% of the light p
ID: 570095 • Letter: W
Question
Week 4 -Spectroscopic analysis of aspirin re-Lab Questions If 25% of the light passing through a sample is Transmitted, what is the Absorbance A of the solution? B?"complexes with Thiourea to form a colored Complex which Absorbs light at = 470 nm with an Extinction Coefficient of = 9320 M-1cm-1. What is the concentration of the complex in a solution that has a measured Absorbance A-0.265 in 1.00 cm cell. 3. When comparing the absorbance of two solutions of the same substance but of different concentrations. Solution A has an absorbance greater than that of the reference solution. How would you conclude about the concentration of solution A compared with the reference solution?Explanation / Answer
1. Absorbance = 2 - log(%T)
with,
%T = 25%
we get,
absorbance = 2 - log(25) = 0.602
2. concentration of complex in solution = absorbance/molar absorptivity x path length
with,
molar absorptivity = 9320 M-1.cm-1
path length = 1 cm
absorbance = 0.265
we get,
concentration of complex = 0.265/9320 x 1 = 2.84 x 10^-5 M
3. A solution of higher concentration would absorbs more light than a solution of lower concentration. If we were to take absorbance measurement of a reference blank solution and compare it with a solution of substance of unknown concentration, we would get higher absorbance value for unknown concentration solution, confirming this has greater amount of substanvce dissolved in it.