The Principle of Corresponding States and Sample Problems

Abstract

The material presented in this lecture is adapted from Chapter 8 in T&M. In this Lecture, we will continue discussing EOS of pure materials (n = 1). First, we will discuss the Redlich-Kwong EOS. Second, we will solve Sample Problem 18.1 to calculate the parameters, a and b, in the van der Waals EOS presented in Lecture 17 using the critical point conditions. We will also solve Sample Problem 18.2 to express the van der Waals EOS using reduced coordinates. Third, we will discuss the Peng-Robinson EOS and the Virial EOS, including solving Sample Problem 18.3 to calculate the second virial coefficient in the case of excluded-volume interactions. Fourth, we will introduce the two-parameter principle of corresponding states and show that it needs to be generalized to encompass all the fluids in nature. Specifically, we will introduce the three-parameter Pitzer compressibility factor correlation approach, which introduces Pitzer’s acentric factor as the third correlative parameter. Fifth, we will show how to calculate the Pitzer’s acentric factor using experimental vapor pressure data. Finally, we will discuss how to use graphical representations to calculate the compressibility factor, whose knowledge is equivalent to knowing the fluid EOS.