Elementary Concepts of Specific Heats

Abstract

The specific heat of a substance is defined as the quantity of heat required to raise the temperature of a unit mass of the substance by a unit degree of temperature. To some extent, the specific heat depends upon the temperature at which it is measured and upon the changes that are allowed to take place during the rise of temperature. If the properties x, y,..., are held constant when a heat input dQ raises the temperature of unit mass of the substance by dT, then

$$ {C_{x,y,...}} = \frac{{\lim }}{{dT \to 0}}{\left( {\frac{{dQ}} {{dT}}} \right)_{x,y,...}} $$

((1.1))

The specific heat, sometimes called the heat capacity, is in general a positive quantity. In the absence of any rigid convention, it seems best to use the term specific heat when referring to 1 g of the material and the term heat capacity when a more general amount of the material, i.e., a gram-atom or a gram-molecule, is involved.