The SI unit for energy is the joule:
A joule is defined as: 1 J = 1 kg • m2 / s2
A calorie is a non-SI unit of heat. The unit was originally defined as the amount of heat required to raise the temperature of one gram of water by one Celsius degree.
Science, which uses SI units, defines a calorie in terms of joules:
1 cal = 4.184 J (exactly)
Most of us usually think of the word "calorie" in terms of food. The interesting thing is that a food Calorie is not the same as a heat calorie!
Notice in the sentence above, the food Calorie begins with a capital C. This is significant!
1 Cal = 1000 cal = 1 kcal
So a food Calorie is actually 1000 calories, or a kilocalorie! For roughly every 3500 Cal we consume but do not burn up through activity, we store 1 pound of body fat.
The most common method for determining the approximate available energy content (Cal) of a food is to determine the number of grams of fat, protein, and carbohydrate in the food, then multiply each mass by the appropriate energy value.
The food energy values are:
- 9 Cal per gram of fat
- 4 Cal per gram of protein
- 4 Cal per gram of carb
The approximate food value per serving is provided on the food label.
You are familiar with this heat equation: q = s X m X ΔT
The specific heat of water is 1.0 cal per g per oC, or 1 Cal per kg per oC, which means that the input of 1.0 cal of energy will cause the temperature of 1.0 g of water to raise 1 oC. By measuring the temperature change in a known mass of water caused by the energy released by the combusion of a peanut, you can calculate the amount of energy produced.
Remember: 1 milliliter of water has a mass of 1 gram.
A "pop can" calorimeter will be used to gather data for this lab.
