Just as rocket feul provides the energy need to launch the Space Shuttle, so the food you eat contains fuel that provides your body with the energy you need every day. This fuel is in the form of stored energy called potential energy. You cannot measure the amount of potential energy in food directly. Instead, you can measure the heat energy, in calories, gained by the water when a sample of food is burned. The heat energy gained is equal to the heat energy lost by the burning food.

Materials: triple-beam balance, assorted food samples, flask matches, ring stand and clamp, paper clip, aluminum pie plate, Celsius thermometer, clock or watch.

Procedure:

1. Read all insturctions before you begin the lab experiment.


2. Make sure to wear your saftey goggles at all times.


3. Find the mass of the empty flask in grams. Enter the weight here:


4. Half fill the flask with water. And find the mass of the flask and the water. Enter this value here:
   Then subtract the weight of the flask alone from the weight of the flask with the water. Record this final mass in the data table.


5. Clamp the flask onto the ring stand. Measure and record the temperature of the water (Ti).


6. Carefully straighten the paper clip and stick it through the food sample.


7. Position the paper clip so that the ends rest on the edges of the pie plate.


8. Use a match to ignite the food sample. CAUTION: be careful when using matches. Once the food begins to burn, blow out the match and dispose of it safely..


9. Place the pie plate directly below the flask. Let the food burn for 3 minutes and then blow out the flame. Record the temperature of the water as Tf in the data table..

Observations
Data Table

Analysis and Conclusions:

1. Use the following equation to calculate the heat energy gained by the water in the flask as the food burned:
   Heat Gained= Mass x Change in temperature x Specific heat
   

   = Mass x (Ti – T f) x 1 cal/g. deg. Celsius










2. How much heat energy was lost by the burning food sample?









3. Share you results with the rest of the class. Make a class data table showing the results for the different food samples tested. Which food released the most heat energy? Which released the least?









4. Most of the heat energy lost by the burning food was absorbed by the water in the flask. What might have happened to any heat energy that was not absorbed by the water?













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