Heat Capacity

Calorimetry is the study of heat and heat energy. A calorie is a unit of heat energy in the British system of measurement. In the metric system, energy is measured in joules, and one calorie equals 4.184 joules. When any substance is heated, the amount of heat required to raise its temperature will depend on the mass of the object, the composition of the object, and the amount of temperature change desired. It is the temperature change and not the individual starting and final temperatures that matters. The equation that relates these quantities is

where q is the quantity of heat (in joules), m is the mass of the object (usually in grams), Cp is the heat capacity (usually in joules/gram degree,) and DELTAT is the change in temperature (in degrees Celsius). The amount of heat required depends on the mass to be heated (i.e., it takes more heat energy to warm a large amount of water than a small amount), the identity of the substance to be heated (water, for example, has a high heat capacity and heats up slowly, while metals have low heat capacities and heat up quickly), and the temperature change (it requires more energy to heat up an object by 60 degrees than by 20 degrees).