This man's namesake elast
This man's namesake elasticity describes surface tension resistance when a surface is stretched, and can be applied to surface-tension-related mass transfer in an effect named for this man and Marangoni.  For a mixture at constant temperature and pressure, the change in the chemical potential of the system can be obtained using an equation named for this man and Duhem.  Another equation named for this man is used to calculate the degrees of freedom of a system depending in part on its number of components.  For 10 points, name this man with a namesake phase rule and a thermodynamic quantity useful in predicting the spontaneity of a chemical reaction, his free energy.
This man's namesake elasticity describes surface tension resistance when a surface is stretched, and can be applied to surface-tension-related mass transfer in an effect named for this man and Marangoni.  
Josiah Willard Gibbs