Heat capacity:
Heat capacity of a substance is defined as the heat transfer necessary to bring about a change in the temperature of unit amount of substance by one degree centigrade. Since it is heat transfer which is a path function, it depends upon the way heating is done. For example gases can be heated to increase the temperature by two different methods. The unit quantity of gas taken in container with rigid wall, when heated its volume remains constant. Another method is to have the wall which is flexible. If the piston is movable in the piston and cylinder arrangement, gas when heated pushes piston and pressure will be constant. Even if we take unit amount of gas in both these heating methods, it is observed the heat transfer is not the same.
Heat capacity of a substance is defined as the heat transfer necessary to bring about a change in the temperature of unit amount of substance by one degree centigrade. Since it is heat transfer which is a path function, it depends upon the way heating is done. For example gases can be heated to increase the temperature by two different methods. The unit quantity of gas taken in container with rigid wall, when heated its volume remains constant. Another method is to have the wall which is flexible. If the piston is movable in the piston and cylinder arrangement, gas when heated pushes piston and pressure will be constant. Even if we take unit amount of gas in both these heating methods, it is observed the heat transfer is not the same.
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