Ashley Brannan

English 202c Section 902 Using a Calorimeter

A Useful Guide to Assembling and Using Calorimeter to Measure the Energy of a Peanut in the Chemistry Lab

Introduction The purpose of this instruction set is to teach nutrition students how to make and use their calorimeters for first time use during their chemistry labs. A calorimeter is an instrument that is used to measure the heat energy that is released by a food product. You can then use the heat energy value to get the caloric value of the food through a set of equations. In this instruction set, you will learn how to use calorimeter through an example problem that is the most common experiment done with a calorimeter: burning a peanut.

Things You Will Need - All of these materials will be found in the front of the room for your experiment. You must go and grab them and bring them back to your station. o A metal can with the top removed o A heavy wire stand to hold the peanut o An adjustable rubber clamp o A metal stand to hold the wire and can. o 150⁰ Celsius thermometer o A graduated cylinder . 100 mL o A funnel o A Long Handled Lighter o A piece of weighing paper o A scale o A peanut o Ice WARNINGS! o When in the laboratory, always wear safety goggles. o Warnings for the example lab (burning a peanut) if you perform it: . For this instruction set, the example that you may follow will use nuts. If you have an allergy, tell your lab assistant immediately. . The metal stand that will be holding the sample will get hot during the reaction that will take place, handle it with tongs. . Do NOT eat any of the foods used in this lab. . Avoid burning yourself when using the lighter to burn the peanut. o Remember if you do perform this lab, this instruction set is meant as a guide in correspondence to your lab, therefor if you need any clarification or have any questions, your lab assistant will be able to fully help you.

Using Your Calorimeter for an Experiment 1. Once you have all of your materials at your station, you need to take your metal can and using a paper towel (dry), wipe any materials (usually carbon matter) off of it. Make sure there is no residue on the can. 2. To set up the apparatus and make it easier for you to follow, refer to Figure 1. Figure 1. The Calorimeter. A – The metal stand, B – The rubber clamp, C – The wire to hold the peanut, D – The metal can, E – The peanut. (Do NOT place the peanut on the wire, yet)

A D

B

E

C

3. Once you have set up your calorimeter, remove the metal can form the adjustable clamp. Then fill the can so that it is half full with ice. 4. Take your peanut, weigh it, and record its mass. Also, grab a piece of weighing paper and record its mass. 5. Place the peanut on the wire stand and light it using the long handled lighter. Once the peanut is lit, then put your can that is filled with ice on top of the burning peanut. Make sure your can is just touching the of the burning peanut’s flame. a. Precaution: If your peanut does not burn fully and the flame goes out, just relight it to finish up this step. If this happens, be sure to remove the can when light the peanut. 6. Once the peanut is done burning, the remaining remnants (charcoal) should be collected and put on the weighing paper from Step 4. Weigh the remnants. a. Use this information to calculate the mass of the remaining material. i. Take the initial mass of the peanut minus the remaining material. 7. Using the adjustable clamp as tongs, pour the liquid water, NOT any of the ice, out of the can and into the graduated cylinder, using the funnel if necessary. Record the volume of the water that is collected. 8. You must repeat steps 1 through 7 two more times. This will give you a good average for your experiment.

Using the Measurements Collected in the Above Section to Determine the Energy of a Peanut 1. To determine the calories in the peanuts that use measured, first you must average the three measurements that you recorded for mass of the peanut (the mass that was recorded after you

subtracted the final remnants from the initial mass). Do this by adding Peanut One (P1), Peanut

Two (P2), and Peanut Three (P3) together, and then divide by three. You also need to use the same equation but instead of masses take the water volume that was produced and do the same calculations. a. The Equation looks like this:

i.

2. You then need to calculate the heat produced by the peanuts. To do this, you need to take the mass of the water (this is the same number as volume, but instead of mL as the unit it is grams) and multiply it by 80 calories/ gram. 80 calories/ gram, if you do not remember, is the heat needed to melt one gram of ice. a. The equation looks like this:

i.

1. qpeanut represents the heat produced by the peanut in calories

2. mwater represents the mass of the water in grams 3. 80 cals/gram represents the heat of fusion of ice (the amount of heat that is required to melt one gram of ice) 3. You then need to determine the heat, in calories, generated by the one gram of your peanut burning. To do this, you need to take the heat produced by the peanut that you found in the previous step and multiply it by the mass of the peanut from the first step in this section. a. The equation looks like this:

i.

1. q represents the heat produced per gram of the sample peanut in calories

2. qpeanut represents the heat produced by the peanut in calories

3. mpeanut represents the mass of the peanut that burned in grams 4. Being a nutrition student in this lab, you are required to convert this calorie number from a chemistry calorie to a nutrition calorie (also known as kilocalorie or Calorie, capital C). a. The equation to do this looks like this:

i.

1. q represents the heat generated per gram of sample in calories (from previous step) 5. Then, because the entire purpose of this lab is to test to see if you can accurately find the amount of calories in a gram of peanut, you must then grab the nutrition label which you grabbed the peanut from and calculate the calories per gram. a. To do this you must take:

i.

6. You can now compare your findings to the one that you get from the label.

Conclusion This instruction set is to help you assemble and use a calorimeter in the chemistry lab or if you want to create your own at home, which precede with caution if you do. After reading this instruction set, I hope that I shed some light on the lab that is to come in your chemistry classes.