A Beer’s Law Investigation Online REPORT SHEET

Name:                                                                _ Partner:

Section: _ Instructor: _                                                              Date:                        _

SHOW YOUR CALCULATIONS ON THE SECOND PAGE OF THIS REPORT. ATTACH A COPY OF YOUR CALIBRATION CURVE & SPREADSHEET.

1. Data table 1: Use M1V1=M2V2 to calculate the initial volume of the stock solution put into the beaker in simulation 1.
2. Data table 2: use Beer’s Law (Abs= εlc) to calculate the molar absorptivity ε, for each of the 5 standard solutions.  Watch significant figures!  Be sure to convert the concentration data from Table 1 to millimolar by dividing the concentration by 10-3.
3. Determine the average ε value.
4. Se the average ε value to calculate the concentration of the unknown Red Drink.
5. Plot the data
6. Compare with the concentration interpolated from the graph/data with the calculated data.
7. Answer the questions.

  BAKS  Rev 04-22 -2020

Data Table 1 for Concentrations  (Concentration Simulations will be used)

                                                   Concentration of the Stock Solution                          M

Concentration Simulation Sample No.	Volume of the Stock Solution Drink Mix (V1) L	Concentration of the Stock Solution Drink Mix (M2) M	Final Volume of the Stock Solution Drink Mix (V2)   L
S1
S2
S3
S4
S5

Data Table 2 for Concentrations and Absorbance (Both Simulations will be used)

Wavelength  nm

                                                                               Pathlength                  cm

Concentration Simulation Sample No.	Concentration Diluted to (x10-3) for use with the Beer’s Law Simulation	Absorbance	ε
S1
S2
S3
S4
S5
Unknown

Average ε_________________

     Calculated Unknown Concentration ________________

Interpolated/data Unknown Concentration __________________

-2020

Questions

1. What color is the light beam at the wavelength being used before it enters the solution.
2. What happens to the color of the light beam at the wavelength being used as it exits the solution while the concentration increases.

There is a decrease in the quantity of light that is being transferred and the total

• What is happening to the in the solution to the Energy from the light, and how does it relate to the color of the solution.  (Think back to the Electronic Structure Flame Test)
• Compare the molar absorptivity for each of the solutions.  Do they agree with each other?  Are they constant?

• Compare the numerical value of your average molar absorptivity with the slope of the linear regression curve on your calibration curve. What does the slope of the line tell you?

• Compare the calculated concentration of the unknown Red Drink with interpolated value from the graph.  Are they similar?  What would cause a difference?