Final answer:
J. Willard Gibbs is famous for his work in the field of physical chemistry. He developed the concept of Gibbs free energy, which is a measure of the energy changes associated with chemical reactions.
Step-by-step explanation:
J. Willard Gibbs is famous for his work in the field of physical chemistry. He developed the concept of Gibbs free energy, which is a measure of the energy changes associated with chemical reactions. His series of papers entitled 'On the Equilibrium of Heterogeneous Substances' laid the foundation for the field of physical chemistry and is considered one of the great achievements of the 19th century.