Saved Bookmarks
| 1. |
Derive the various mathematical statements of the first law. |
|
Answer» Solution :Mathematical STATEMENT of the First law of Thermodynamics is `DeltaU=q+w` Case 1: For a cyclic process involving isothermal EXPANSION of an ideal gas `DeltaU=0` `therefore` q=-w In other words, during a cyclic process, the amount of heatabsorbed by the system is equal work done by the system. Case 2: For an isochoric process (no change in volume) there is no work of expansion `DeltaV=0` w=0 `DeltaU=q_v` In other words, during isochoric process, the amount of HEAT supplied to the system is converted to its internal energy. Case 3: For an adiabatic process there is no change in heat i.e.q=0. Hence q=0 `DeltaU=w` In other words, in an adiabatic process, the decrease in internal energy is exactly equal to the work done by the system on its surroundings. Case 4 : For an isobaric process. There is no change in the pressure. REMAINS constant. Hence `DeltaU=q+w` `DeltaU=q-PDeltaV` In other words, in an isobaric process a part of heat absorbed by the system.is used for PV expansion work and the remaining is added to the internal energy of the system |
|