Thermodynamics - Specific Heats; The Calorie

An important characteristic of materials is how much energy in the form of heat it takes to raise the temperature of some material by one degree. It depends upon the type of material being heated as well as its amount. The traditional basic unit, the calorie, is defined as the amount of heat that is needed to raise one gram of water by one degree Celsius. In terms of mechanical energy units, one calorie equals 4.186 joules (J).

The corresponding amount of heat necessary to raise the temperature of other materials is given by the specific heat capacity of a material, usually denoted by c. It is the number of kilojoules (kJ) needed to raise 1 kg of the material by 1°C. By definition, the value for water is 4.186 kilojoules. Typical values for c in kilojoules per kg (kJ/kg), at 0°C, are: ice, 2.11; aluminum, 0.88; copper, 0.38; iron, 0.45. It should be noted that water needs more heat to bring about a given rise in temperature than most other common substances.