Science Buddies: "Ask an Expert"

I am attempting to complete the science fair project entitled "Burning Calories: How Much Energy is Stored in Different Types of Foods". While doing the experiment, I encountered a problem. After solving the formula, I found an extremely unrealistic caloric content of the tested food. I used a Peak Frean cookie as the test food and 175mL of water. The change in temperature was of 0.7 degrees Celsius, thus giving us a caloric content of 122.5 calories. The Peak Freen weighed 1.22 grams and the bag in which it was packaged read that there were 100 calories per 30 gram serving. Since I got 122.5 grams per 1.22 grams, I have a hunch I made a mistake. Would you please help me understand where I went wrong.

Thank you

Hi Panacoda,
122.5 calories per 1.22 grams is equivalent to 3012 calories (or 3.012 Calories) per 30 grams. Is that what you got? If you don't know what I mean by "calories" versus "Calories", 1 Calorie = 1000 calories. (See the section "A Note on Units" in the project description.) The food packaging reports values in the units of "Calories", so their value is much higher than yours.

If these measurements and calculations are correct, it seems that you found a much lower caloric content than reported on the package. Did the cookie burn completely? Did some of the heat escape? These are some sources of experimental error that you could consider.

Looking forward to hearing more,
Chris

Thank you very much Chris.