Macleod equation and constant in pure, binary and ternary systems

Abstract

The Macleod equation establishes a linear relationship between surface tension and the fourth power of the density difference between liquid and vapor, expressed as$\sigma =C_{Macleod}{({\rho }_l-{\rho }_v)}^4$. This study demonstrates by a practical and empirical approximation with critical exponents and the theory of corresponding states, the foundations behind Macleod's proposal and extends this equation to binary and ternary systems exhibiting liquid-liquid equilibrium. Additionally, it offers a thermodynamic perspective on the Macleod constant through a novel variable termed the entropic molar volume, along with other functions.