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Fresh Or Canned Calories?

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Author: Muriel Gerhard

Grade Level: 9th -10th; Type: Chemistry

Objective:

Determine whether fresh vegetables have more calories or less calories than canned vegetables. 

Research Questions:

  • What is a calorie?
  • What is a Calorie?
  • What is metabolism?
  • How do we determine the caloric values of foods?
  • Why is caloric content an important piece of information?
  • What is the connection between obesity and caloric intake?
  • What can be done to conquer the continued increase in obesity in this country?

On the information level, the student will learn how a calorimeter works and how specialists in nutrition determine the caloric value of foods which our bodies oxidize and metabolize providing us with the essential energy for life. The student will set up a simple calorimeter and use it to estimate the amount of energy or specifically the number of calories a specific food will yield. In our bodies in the process of metabolism, foods are broken down by enzymes within the mitochondrial cells. The result is energy. Energy is measured in Calories. The amount of energy required to raise the temperature of 1 kilogram of water by one degree Celsius is equal to one Calorie of energy.

It is important to understand how the calorimeter works. It is set up so that a known quantity of food is burned which releases its energy in the form of heat. The heat is transferred to a given volume of water. We determine the increase in the water temperature and multiply it by the mass of water in the calorimeter and determine the amount of energy actually absorbed from the oxidation of the food source. We use the following equation: Q=mc (Tfinal –Tinitail). Q is a measure of the heat capture in calories. M is the mass of the water in grams. C is the heat capacity of the water, 1 calorie per gram per degree Celsius. T final l is the final temperature of the water following combustion of the food. T initial is the initial temperature of the water before combustion of the food.

On the process level, the student will employ the scientific method, formulate a hypothesis and provide a rationale for the hypothesis, conduct the experiment, record and analyze the data, write up the final report and include the bibliography.

Materials:

  • Fresh peas
  • fresh corn
  • canned peas
  • canned corn
  • triple beam balance
  • thermometer
  • two metal coffee containers
  • a Celsius thermometer
  • a metal rod
  • a water bath
  • a cork

The vegetables can be purchased from the super market and the science equipment may be borrowed from the school science lab or purchased from Science Kit.

Experimental Procedure:

  1. Gather all of the materials you will need for this project. These include:  Fresh peas, fresh corn, canned peas, canned corn, triple beam balance, thermometer, two metal coffee containers, a Celsius thermometer, a metal rod, a water bath, a can opener and a cork. Using a can opener, remove the bottom of a large tin and remove the lid.
  2. Copy the Data Chart provided below so that you can readily record your observations.
  3. Drill several holes in the base of the large tin.
  4. In a smaller tin that can fit inside the larger tin, drill two holes on either side of the container to allow for a metal rod to pass through the holes and rest the small tin inside the larger tin.
  5. Place the apparatus over a cork with a linear wire sticking into the cork. The wire and cork will support the suspension and burning of the food substance beneath the suspended smaller tin can inside the larger tin can.
  6. Select a fresh pea and a canned pea of identical masses to begin the experiment. Use a triple beam balance to measure the mass of the peas.
  7. Stick the wire of the cork into the fresh pea and suspend the pea under the tin can inside the calorimeter.
  8. Fill the smaller tin can with a known volume of water. This quantity is a measure of the mass of water in the calorimeter.
  9. Record the temperature of the water in your data chart this quantity is a measure of the initial temperature, T initial.
  10. Using the matches, light the fresh pea and allow the pea to burn to completion inside the calorimeter underneath the suspended water container.
  11. Stir the water inside the small container and record the temperature of the water. This quantity is a measure of the final temperature, T final.
  12. Carefully remove the burned fresh pea when it has cooled and measure the mass of the fresh pea using a triple beam balance.
  13. Repeat steps 5-11 for the canned pea for comparison, for example fresh and canned corn.
  14. Substitute the values of the average final and initial temperatures, masses of water and food into the equation for energy transfer and solve to find the value of Q for each food source, a measure of the heat capture in calories.
  15. Record all your data in the data chart.
  16. Analyze the data. Draw your conclusion. Review your hypothesis.
  17. Write up your report. Make certain to include your bibliography.

Data Chart

Food Samples
Mass of Food
Initial Water Temp
Final  Water Temp
Value of Q
Fresh pea
 
 
 
 
Fresh corn
 
 
 
 
Canned  pea
 
 
 
 
Canned corn
 
 
 
 

 

Terms/Concepts: Calorie; calorie; metabolism; mitochondrial cells; heat energy transfer; calorimeter

References:

 

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