What’s in a Nut?

Calorimetry Lab

Introduction:

The evening before a marathon, runners are advised to eat a huge plate of pasta. Pasta, a carbohydrate, is a terrific source of energy, or fuel for the body. Different foods contain varying amounts of energy, which is calculated as calories or kilocalories. In other words, calories are a way to measure the energy you get from the food you eat.

In this activity, you will demonstrate how calories are measured. First, you need to set up an inexpensive calorimeter. A calorimeter is a device that measures the transfer of heat energy during a chemical or physical change. One type of calorimeter contains a combustion chamber surrounded by water. When matter is placed in the chamber and physically or chemically changed (usually by burning), the temperature change of the surrounding water is measured and used to determine the energy (calorie) content of the sample. This lab indirectly measures food Calories (kilocalories) using a homemade calorimeter.

Materials:

• Thermometer Holder

• ring stand

• wire ring

• large cork

• matches

• balance

Procedure:

  1. Place two straightened paper clips (or pieces of a wire hanger) into opposing holes in the soda can. Hang the can in the wire ring on the ring stand and adjust the height accordingly. This apparatus is your calorimeter.
  2. Measure 200 mL of tap water using the graduated cylinder. You might need to think for a moment on how to do this. The accuracy of the amount of water is very important for this calculation. Pour the water into the can
  3. Manipulate the third paper clip so it has a base and a place to either skewer your food or make a platform for it.
  4. Place the thermometer into the mouth of the can. Remember to suspend the thermometer in the water when taking a temperature reading. Before going any further, check the apparatus to make sure that everything is secured.
  5. Choose a nut, measure its initial mass and record in the data table (below). When taking mass readings, be sure the same weight boat each time. DO NOT zero the scale with the weight boat on it.
  6. Take an initial temperature reading of the water in the can and record in the data table.
  7. Place the nut on its stand. Use a match to set the nut on fire. This may take several tries. Make sure the fire heats the can. If it doesn’t, readjust the height of the can/ring. Closely observe the nut as it burns. If the nut falls off the stand, start over immediately.
  8. As soon as the nut stops burning, immediately take a final water temperature reading and record it in the data table.
  9. As soon as the nut has cooled, use tongs or fingers to lift the burned remains onto the weight boat and then the balance. Take a final nut mass and record in the data table.
  10. Empty your can calorimeter and repeat steps 2-11 with 3 other food choices (mini-marshmallow, potato chip, several cheerios, ect.)

Sample Data Table: You will need 4 data tables, one for each food

Mass of Food
(grams) / Water Temp.
(oC) / Water amount
(grams)
Initial Reading
Final Reading
Difference

Calculations: (Remember, SHOW ALL WORK)

  1. Calculate the total energy for each food tested (one nut, mini-marshmallow, potato chip and several cheerios).
  2. Find the kcal for one gram of food. (Hint: Energy per gram of food)

Conclusion:

  1. Restate the purpose of the lab.
  2. Briefly summarize the procedure.
  3. Summarize your results (energy from 1 piece and food calories per gram of food tested)
  4. List three sources of error and state if that error would have made your results too large or too small.
  5. How could this lab be improved?