CHM 1045L Lecture Notes - Lecture 3: Caffeine

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16 Nov 2015
School
Course
Calculating Your Jitters
Date Performed: 09/15/2015 Alexander Wilsey
Date Submitted: 09/22/2015
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Lab 03 - Calculating Your Jitters: The Mass Percent of Caffeine in Coffee: Calculating Your Jitters
Wilsey, Alexander
Abstract
Caffeine is a stimulant, also considered a drug, that affects a person's central nervous system. However,
many people tend to ignore the fact that they consume this drug on a regular basis. Whether it be in their
morning cup of coffee or in their favorite soda, caffeine can be very dangerous if excessive consumption
occurs.
Since caffeine is one of the main components of coffee, the mass percent is calculated to see what
percent of coffee is made up of caffeine. The way that the mass percent of a substance is calculated is to
take the mass of the total solution and divide that by the mass of the isolated solution. But in order to get
the mass percent, the mass of the caffeine must be found. This is done by finding the LD50.
The purpose of this experiment is to calculate the amount of coffee needed to be in jeopardy of getting
the "caffeine jitters." To get the jitters, one would need to consume approximately 20% of the LD50 of
caffeine, or the lethal dosage for 50% of the population. In order to calculate the lethal dosage, the
formula used is 150mg of caffeine per kg of body weight. In the experiment, if caffeine is extracted from
30.0mL of coffee and the LD50 is calculated, then it will require approximately 5 cups of coffee to get
the jitters, and 25 cups to reach the lethal dosage.
This hypothesis was tested by putting 30.0mL of coffee and around .600g of Sodium Carbonate in a
separatory funnel. Along with the mixture, Dichloromethane was added to help separate the caffeine
from the coffee. Once mixed and settled, the clear liquid was drained from the funnel into a beaker. That
beaker was then put on a hot plate to evaporate all of the leftover solution so that only the pure caffeine.
The caffeine was weighed and was used to find the mass percent by dividing the mass of the total
solution by the mass of the caffeine times 100 percent.
The LD50 was calculated by dividing 150mL caffeine by body mass in kg. This gave the amount of
caffeine in milligrams. The amount was converted into grams and then multiplied by 30 mL and then
decided by the mass of the caffeine calculated before. This gave us the amount of mL of caffeine that it
would take to kill half of the people in the population.
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Lab 03 - Calculating Your Jitters: The Mass Percent of Caffeine in Coffee: Calculating Your Jitters
Wilsey, Alexander
Procedure
Lab 3 Calculating Your Jitters: The Mass Percent of Caffeine in Coffee. General Chemistry 1 Lab
Manual. Bluedoor Publishing, LLC. 2015. 9/15/2015. https://www.bluedoorlabs.com/online_manual.
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