Beers Law Lab

Klara Beinhorn P7

What is Beers Law?

Beers law says that the amount of light transmitted in a substance is in direct proportion to the percent of concentration. This means that if you have a higher amount of light transmitted, then there it is less concentrated. Also means if a substance has a high concentration, then less light will be able to be transmitted.

Background of Anesthesia

  • Anesthesia is a practice of medicine that works by preventing sodium ions in the body from going to one nerve cell to the next, therefore preventing the feeling of pain
  • It is mostly used for medical procedures

How to Make a 40% Percent Solution

  • Know what your solute is (an example of a solute is food coloring)
  • Know what your solvent is (an example of solvent is water)
  • For every ten ml, 6 ml should be water and 4 ml should be food coloring
  • For example, if I want 10 ml of solution, I am going to fill 4 ml with food coloring
  • Next, I am going to fill the other 6 ml with water
  • Now you have a 40% solution
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Background of Beers Lab

  • Aunt Elda had an appendectomy and therefore needed anesthesia
  • Aunt Elda died during the procedure and we need to figure out why
  • The normal amount of anesthesia concentration is 40%, so did she get too much?
  • Less concentration transmits more light, while more concentration transmits less light
  • The lighter green cuvettes had less concentration therefore transmitted more light and that was why they were lighter than the more concetrated darker cuvettes
  • A Colorimeter is used to measure absorbance
  • Then we plot the percent concentration and absorbance on the graph
  • Next, we used a line of best fit to figure out the percent concentration of Aunt Elda's cuvette of anesthesia based on its absorbance


- Anesthesia article

- Computer

- Cuvettes

- Colorimeter

- Paper towels

-Various solutions

Lab Setup

First we gathered all of our cuvettes and filled them with the different percent concentration solutions. Next, we connected our colorimeter to our computer. We tested all of the cuvettes and entered the data into our graph.
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Above you can see the colorimeter which was used to measure the percent of like transmitted along with the absorbance.
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Above are the cuvettes which were used to hold the various solutions. We then put them in the colorimeters to test the absorbance and the light transmitted.
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Above is our lab set up with the colorimeter hooked up to our computer.
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The data above is from using the colorimeter plugged into our computers. The "Conc %" stands for the percent concentration. The "Trans %" stands for the percent of light transmitted through the cuvette. The "Absorbance" is the light absorbed by the solution.
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The graph above is made from using the data points from the table above. As you can see the x-axis is the the percent concentration, and the y-axis is the absorbance.


We used our graph containing our data to figure out if the concentration of anesthesia was too much (maximum is 40%). We then figured the abosorbance for the cuvette containing the solution that was used on Aunt Elda. We used our graph to follow our line of best fit to where the concentration was to the absorbance of Aunt Elda's solution. We then concluded that it was 54.5% anesthesia.

1. Was the concentration of Aunt Elda's anesthesia too strong?

Yes, because it was 54.5% concentration and the maximum is 40%.

2. If yes, how did that cause her death? If no, do you have a hypothesis for the cause of her death?

Too much of the anesthesia shut down her body.

3. How did Beer's Law help you solve this case?

It helped because Beer's Law says the amount of light transmitted through a substance is proportional to percent concentration. Because of this, we were able to follow our line graph and be able to tell the percent concentration based on absorbance.