Thermodynamics is a macroscopic science and its most fundamental level is the study of two physical energy, entropy and quantities. Energy may be regarded as the capacity to do work, whilst entropy (see Topics B4 and G8) may be regarded as a measure of the d is-order of a system chemical reactions. The study of heat and other forms of energy and various related changes in physical quantities such as temperature, pressure, density, etc. Since energy is either released or taken in by all chemical and biochemical processes, thermodynamics enables the prediction of whether a reaction may occur or not without need to consider the nature of matter. However, there are limitations to the practical scope of thermodynamics which should be borne in mind.
The first law:
The first law of thermodynamics illustrate as:
"The total energy of an isolated thermodynamic system is constant".
The first law is often referred to as the conservation of energy, and implies the popular interpretation of the first law, namely that 'energy cannot be destroyed or created'. In other words, energy may be lost from a system in only two ways, either as heat or as work.
ΔQ = ΔU + ΔW