Thermodynamic and transport properties of fluids: SI units

When preparing the necessary revisions of these important and widely-used Tables, the authors took into consideration the fact that the Tables had been used for the solution of problems by many teachers and in many textbooks. Trivial modification of tablated values could therefore inconvenience many teachers and authors. Fortunately, because late `up-to-date' values differ insignificantly from those quoted in the Third Edition, the authors have been able to leave all tabulated values as they were, with the exception of the vlaues of equilibrium constants. Changes introduced into the new edition have almost entirely been concerned with three aspects. (a) The standard pressure, pi, has been moved from 1 atm to 1 bar, in line with the 1982 recommendation of IUPAC. (b) A more satisfactory definition of the equilibrium constant has been adopted, resulting in a quantity which is always dimensionless, and of which therefore a logarithm can legitimately be taken. At the same time the base of the logarithm has been changed from 10 to e. The shifts in standard pressure and base of logarithm have resulted in new numerical values of the equilibrium constant, but these new values are consistent with the old, so that problems will yield the same solutions when worked out with the new values. Notation has been brought into line with the most appropriate of current practice, and in particular molar quantities are designated by the tilde, e.g. molar enthalpy is denoted by h.