Our editors will review what you’ve submitted and determine whether to revise the article.Join Britannica's Publishing Partner Program and our community of experts to gain a global audience for your work!
Reversibility, in thermodynamics, a characteristic of certain processes (changes of a system from an initial state to a final state spontaneously or as a result of interactions with other systems) that can be reversed, and the system restored to its initial state, without leaving net effects in any of the systems involved. An example of a reversible process would be a single swing of a frictionless pendulum from one of its extreme positions to the other. The swing of a real pendulum is irreversible because a small amount of the mechanical energy of the pendulum would be expended in performing work against frictional forces, and restoration of the pendulum to its exact starting position would require the supply of an equivalent amount of energy from a second system, such as a compressed spring in which an irreversible change of state would occur.
Learn More in these related Britannica articles:
thermodynamics: Thermodynamic equilibrium…process is said to be reversible because the system is at (or near) equilibrium at each step along its path, and the direction of change could be reversed at any point. This example illustrates how two different paths can connect the same initial and final states. The first is irreversible…
acid–base reaction…suggested that acid–base reactions are reversible—that is, that the products of the reaction can interact to regenerate the starting material. It also introduced the concept of equilibrium to acid–base chemistry: this concept states that reversible chemical reactions reach a point of balance, or equilibrium, at which the starting materials and…
colloid…generally classified into two systems, reversible and irreversible. In a reversible system the products of a physical or chemical reaction may be induced to interact so as to reproduce the original components. In a system of this kind, the colloidal material may have a high molecular weight, with single molecules…