Question

State limitations of the first law of thermodynamics?

Answer 1

Following are the limitations of the first law of thermodynamics-

1. There is no restriction on the direction of the flow of heat. The first law establishes a definite relationship between the heat absorbed and the work done by a system. However, it does not indicate whether heat can flow from a cold body to a hot body or not.
2. It does not specify the feasibility of the process. For example, when a rod is heated at one end then equilibrium has to be obtained which is possible only by some expenditure of energy.
3. Practically it is not possible to convert the heat energy into an equivalent amount of work.