A law that states that the total quantity of something remains unchanged within a system even though there may be changes taking place within the system such as chemical reactions, changes of states, and other physical, chemical, and biochemical changes. The conservation of mass is a law that states that the total amount of material within a system such as a chemical process remains unchanged. That is, the total amount within the system boundary does not increase nor decline. It forms the basis of a material balance for a process. The conservation of energy is a law that states that the total energy within a system remains unchanged. The Bernoulli theorem is used to show the total energy in a fluid is conserved and takes into consideration pressure-volume, kinetic, and static energies. The total enthalpy of chemical components remains unchanged in spite of any chemical reactions. It forms the basis of an energy balance for a process.