Apparent molar isentropic compressions and expansions of solutions

Isentropic compressibilities of solutions kappa (S) are readily calculated using the Newton-Laplace equation together with measured speeds of sound an d densities. The result is an apparent molar isentropic compression for a g iven solute-j, phi (K-Sj; def) and a limiting property, phi (K-Sj; def)(inf inity). This review examines the definition and calculation of phi (K-Sj; d ef) and phi (K-Sj; def)(infinity), commenting on the related isentropic exp ansions, phi (E-Sj; def) and phi (E-Sj; def)(infinity). We describe the the rmodynamics which underpins the use of isentropic properties in the study o f solute-solvent and solute-solute interactions.