Over a certain temperature interval, the saturation pressure-temperature curve of a substance is represented by an equation of the form ln psat 5 A 2 B/T, where A and B are empirically determined constants.
(a) Obtain expressions for hg 2 hf and sg 2 sf in terms of p-y-T data and the constant B.
(b) Using the results of part (a), calculate hg 2 hf and sg 2 sf for water vapor at 258C and compare with steam table data.