From joules to Calories
In chemistry we can measure heat using two different units: calories and joules. The SI kinetic energy Unit is joules (J). A calorie is defined as the energy needed to raise the temperature of 1 gram of water through 1 °C (or 4.18400 joules).
You know how the nutrition section always has a section for “Calories”? What is it and why do people care so much? A food Calorie is actually a kilocalorie – 1000 calories. A calorie is a measurement of energy like a joule. In other words, it is a number that will show us how much energy we can get from certain foods. But why do we worry so much about foods high in Calories? Think of it this way. Calories are stored in fat so think “Calories in – Calories out = Caloric fat change”. Too much foods like junk food will quickly put fat on your bones and may lead to health problems and diseases like diabetes and heart disease.
- Remember that 1 Calorie (kcal) = 1000 calories (cal) = 4187 joules (J) = 4.184 kilojoules (kJ). How many joules are in 432 calories? How about 432 Calories?
Where else might we use joules? Research!