Limitations of First Law of Thermodynamics

1. According to first law of thermodynamics, when a closed system undergoes a thermodynamic cycle, the net heat transfer is equal to net work transfer. But this definition does not specify the direction in which the energy interaction takes place. It also does not specify the conditions under which these transfers takes place.

2. Heat and work are “ mutually convertible to each other “. This is misleading as work can be fully convertible into heat but heat cannot be fully convertible into work.