A.What does it mean to say that a food molecule "contains" a certain number of calories?

Answer 1

A calorie a unit of energy equal to 4.18J and when a food molecule is claimed to have say 5 calories, this will give your body 5 x 4.18J = 21J of energy.

More often as food is eaten in larger qualities than molecules, the units are mulitplied by 1000 so a banana for example is 108 kcal or 108,000 calories (often misread as just 108 calories).

Answer 2

For general chemistry, it's the amount of energy released when the molecule is broken down, i.e. the bonds between the atoms are broken.

This information is acquired empirically, for a few million molecules, and then converted to the figure per molecule. Or it can be calculated based on the number and type of bonds present.

Because metabolism is incomplete, not all bonds will be broken. AFAIK, the empirical method is what's used to gather that info.

Answer 3

A calorie is a unit of energy not a "thing". It takes 1 calorie to heat 1 liter of water 1 degree. The more calories in a food, the more energy your body can get from it.


Hope this helps!

Answer 4

Many substances including food can be burned in a scientific apparatus called a calorimeter. This measures the amount of heat (calories) that are released from a sample of known weight. This also permits the calories of different foods to be compared. For example, an ounce of fat has more calories than an ounce of protean.