Heat and Thermodynamics

8.3 Specific Heats and Latent Heats

As already stated, thermodynamics deals with the transformation of heat energy into mechanical work and vice versa. By the application of heat, to a body, the thermodynamic state of the body changes and therewith the thermodynamic co-ordinates defining the state also change. Let dp, dv and dθ be the infinitesimally small changes in pressure, volume and temperature of the body as a result of absorption of small quantity of heat dQ. Then from change of any two of these co-ordinates, the quantity of heat absorbed dQ can be calculated. The change in the remaining thermodynamic co-ordinates can be obtained from the changes of the two co-ordinates with the help of the equation of state.

Thus,

 

dQ = k dθ + ℓ dv