Calorie (cal;
small calorie): An energy unit equal to the approximate
amount of energy required to raise one gram of water
by one degree Celsius, or about 4.2 joules.
(The unit is only approximate because the heat
capacity of water
varies with the temperature of the water.)
The
calorie is not part of the International
System of Units, but is still widely used. Not to be
confused with a food
calorie (large
calorie), which is equal to one kilocalorie.
Raising the temperature of one
liter of water
from 20 oC (about room temperature) to 100 oC
(water'sboiling
point) requires approximately (1000 grams x 80 oC)
= 80,000 calories (80 kcal).
