The relation between information and classical thermodynamic transformations is investigated. A probabilistic facet of reversible transforms is first illustrated. A method for quantifying the information associated with heating, cooling, expansion, and compression is then presented. Several applications are illustrated for a single-component van der Waals fluid. The significance is discussed in terms of dimension and measurement resolution properties, critical point behavior, and the algorithms designed for heat engines. The uncertainty in the state point position due to fluctuations is well-established for equilibrium systems. What is examined here is the uncertainty surrounding an extended locus of points. The Shannon information serves as a useful tool for quantifying this uncertainty.