limitations of first law of thermodynamics:

There are some limitations of First Law of Thermodynamics.

1. When a closed system undergoes thermodynamic cycle, the average heat transfer is equal to average work transfer. The law does not specify direction of flow of heat and work nor gives any condition under which transfer of energy take place.

2. The heat energy and mechanical work are convertible mutually. The mechanical energy can be totally converted into heat energy but only a part of heat energy is converted into mechanical work. Thus, there is limitation on the amount of conversion of one form of energy into another form.