Comparison between work and heat:

Similarities:

· Both are path functions and inexact differentials.

· Both are boundary phenomenon i.e., both are recognized at the boundaries of the system as they cross them.

· Both represent transient phenomenon; these energy interactions occur only when a system undergoes change of state i.e., both are associated with a process, not a state. Unlike properties, work or heat has no meaning at a state.

· A system possesses energy, but not work or heat.

· Concepts of heat and work are associated not with a ‘store’ but with a ‘process’.

Dissimilarities:

· Heat is energy interaction due to temperature difference only; work is by reasons other than temperature difference.

· In a stable system, there cannot be work transfer; however there is no restriction for the transfer of heat.

· The sole effect external to the system could be reduced to rise of a weight but in the case of a heat transfer other effects are also observed.

· Heat is a low grade energy whereas work is a high grade energy.