Monolayers are one of the most basic structures in living things. They make up the interfaces in plants, in your cells, and on the surface of your lungs. Phase equilibria of these monolayers, conditions at which both liquid and vapor phases may coexist, are of particular interest as they give insight into the phase behavior of biological interfaces in general. Monolayers made of Pentadecanoic acid, a simple fatty acid, have been the focus of previous research on this topic. In particular, chemical simulations of these monolayers have been conducted to alleviate the difficulty in experimentally determining phase equilibria as well as to provide structural information at the atomic level. Simulations in the past, however, have produced somewhat inconclusive results due to limited computing power. This project seeks to improve upon prior research through larger and longer simulations with more accurate molecular models.