Thermodynamics of the Lambda Transition in Liquid Sulfur

Abstract

The thermodynamics of the lambda transition in liquid sulfur is examined in terms of the Pippard relations. Using West's specific-heat results and critically evaluated thermal-expansion data, the initial slope of the λ line in p—T space, (∂p/∂T)λ, is estimated as ∼−42 bar deg−1. It is suggested that the ultrasonic measurements for liquid sulfur are inadequate, especially near the lambda transition, and that there is, hence, insufficient knowledge of the compressibilities. The present estimate for (∂p/∂T)λ compares favorably with that predicted from a theory of equilibrium polymerization and the two approaches are suggested to be complementary.