Beers Law

By; Shane Minor

Procedure


1. Connect the Colorimeter to the computer interface.Prepare the computer for data collection by opening the file "11b

Beer's Law" from the Chemistry with Computers folder of Logger Pro.

2. You are now ready to calibrate the Colorimeter. Prepare a blank by filling a cuvette 3/4 full with distilled water.To correctly use a Colorimeter cuvette, remember:

• All cuvettes should be wiped clean and dry on the outside with a tissue.

• Handle cuvettes only by the top edge of the ribbed sides.

• All solutions should be free of bubbles.

• Always position the cuvette with its reference mark facing toward the white reference mark at the top of the cuvette slot on the Colorimeter.

3.Calibrate the Colorimeter.

a. Open the Colorimeter lid.

b. Holding the cuvette by the upper edges, place it in the cuvette slot of the Colorimeter. Close the lid.

c. lf your Co lorimeter has a CAL button, Press the < or> button on the Colorimeter to select a wavelength of 635 nm

---- - --{Rea)fOflliis expenment. Press the CAibutton u ntillhe redLED-oegins to flasli. Then release the CAL button.

When the LED stops flashing, the calibration is complete. Proceed directly to Step 7. If your Colorimeter does not have a CAL button, continue with this step to calibrate your Colorimeter.

4. You are now ready to collect absorbance data for the standard solutions. Click I t > collect I. Empty the water from the cuvette. Rinse the cuvette twice with -1 mL water and then fill it 3/4 full with the first sample of 20%. Wipe the outside with a tissue and place it in the Colorimeter. After closing the lid, wait for the absorbance value displayed on

the monitor to stabilize. Then click I Keep Itype 20% in the edit box, and press the ENTER key. The data pair you

just collected should now be plotted on the graph. •

5. Discard the cuvette contents as directed by your teacher. Fill the cuvette 314 full with 40% sample. Wipe the outside, place it in the Colorimeter, and close the lid. When the absorbance value stabilizes, click I Keep I, type 40% in the

edit box, and press the ENTER key.

6. Repeat the steps until you have sampled all of the solutions. When you have finished press I•stop l

7. In your Data and Calculations table, record the absorbance and concentration data pairs that are displayed in the table.

8. Examine the graph of absorbance vs. concentration.To see if the curve represents a direct relationship between these two variables, click the Linear Fit button,. A best.fit linear regression line will be shown for your five data points. This line should pass near or through the data points and the origin ofthe graph.(Note: Another option is to choose Curve Fit from the Analyze menu, and then select Proportional. The Proportional fit has a y·intercept value equal to 0; therefore, this regression line will always pass through the origin of the graph).

9. Rinse your Cuvette with water well and dry it the best that you can. Fill full with the unknown solution. Wipe the outside of the cuvette, place it into the Colorimeter, and close the lid. Read the absorbance value displayed in the

meter.(Important: The reading in the meter is live, so it is not necessary to click l 1• collect lto read the absorbance

value.) When the displayed absorbance value stabilizes, record its value in the Data and Calculations table.





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lO.Discard the solutions down the sink. Proceed directly to Steps 1 and 2 of Processing the Data.

Prelab Questions

PRELAB QUESTIONS:

. Tell me about an experience that you have had with anesthesial (dentist/doctor/???) If you have never had the experience, do you foresee a future experience?

i have had 2 ACL surgeries that used anesthesia.

2. What are characteristics (functions ) of an anesthesia that are desirable?

it numbs an area or the whole body

3. What are characteristics (functions) of an anesthesia that are not desirable (dangerous)?

it can lead to nausea and too much could kill someone

Big image

Graph

As the concentration increases, the absorbance also increases. In this lab we were tasked with seeing if a person would live the percent an anesthesia they were given. If it was under 40%, they would live. as the point shows, it looks to be about 29%, so they should live if the anesthesia was the only factor

Making % solutions

In order to make a % solution, you need to know the amount of liquid you have. If want to have 40% anesthesia, you need to know what your base is. If you have 10 oz of water, to make 40% you would want to to 10/4. This would e 4 oz.