Understanding the rates of chemical reactions is the focus of the physical chemistry field of chemical kinetics, also referred to as reaction kinetics. Contrast that with chemical thermodynamics, which focuses on the direction in which a reaction takes place but says nothing about the pace of the process. Chemical kinetics comprises studies of how experimental circumstances affect a chemical reaction's rate and reveal details about the reaction's mechanism and transition phases, as well as the creation of mathematical models that can also characterise a chemical reaction's features. Chemical reaction is modelled mathematically. Chemical engineers and chemists may use kinetics to better comprehend and characterise chemical processes including the chemistry of biological systems, the proliferation of microorganisms, and the destruction of stratospheric ozone. The design or modification of chemical reactors may also make use of these models to increase product yield, more effectively segregate products, and get rid of by-products that are bad for the environment. Kinetic models can be used, for instance, to determine the temperature and pressure that will result in the best yield of heavy hydrocarbons into gasoline while conducting catalytic cracking of heavy hydrocarbons into gasoline and light gas.