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# Beer's Law for Concentration

1. Calculate the concentration of each calibration standard.
2.Plot the data on the attached graph paper.
3. Calculate the slope. What is the average slope? What are the units?
4.Determine concentration of the diluted unknown.
5. determine the undiluted concentration of the unknown.
The stock solution is 0.027 M KMnO4

Volume of Stock Solution total volume concentration absorbance
Standard 1 1 ml stock 250 ml .15
Standard 2 2 ml stock 250ml .30
Standard 3 4 ml stock 250ml .60
Standard 4 6ml stock 250ml .90

the unknown solution has an absorbance of .42 when 1 ml of the solution is diluted with 4 ml of water.

#### Solution Preview

BEER'S LAW, STANDARD CURVES, AND DETERMINATION OF AN UNKNOWN

The first thing we should do is calculate the actual concentration of the four standards.

Standard 1 is a 1:250 dilution of 0.027 M solution. Therefore, we determine its concentration like this:

0.027 M/250 = 0.000108 M = 0.108 mM

Standard 2 is a 2:250 dilution. Therefore,

0.027 M/125 = 0.000216 M = 0.216 mM

Standard 3 is a 4:250 dilution. Therefore, 0.027 M/62.5 = 0.000432 M = 0.432 mM

Standard 4 is a 6:250 dilution. Therefore, 0.027 M/41.66667 = 0.000648 M = ...

#### Solution Summary

350 words of explained calculation show how to apply Beer's Law to concentrations for calibration standards.

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