CHEMICAL THERMODYNAMICS

By Maria Reinn Trina Soliman

Thermodynamics is an ever evolving subject. Thermo means heat( energy) and dynamics means motion or movement. Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the laws of thermodynamics. Chemical thermodynamics involves not only laboratory measurements of various thermodynamic properties, but also the application of mathematical methods to the study of chemical questions and the spontaneity of processes.

The structure of chemical thermodynamics is based on the first two laws of thermodynamics. Starting from the first and second laws of thermodynamics, four equations called the “fundamental equations of Gibbs” can be derived. From these four, a multitude of equations, relating the thermodynamic properties of the thermodynamic system can be derived using relatively simple mathematics. This outlines the mathematical framework of chemical thermodynamics.

The primary objective of chemical thermodynamics is the establishment of a criterion for determination of the feasibility or spontaneity of a given transformation. Chemical thermodynamics is typically used to predict the energy exchanges that occur in the following processes:

  1. Chemical reactions
  2. Phase changes
  3. The formation of solutions

The following state functions are of primary concern in chemical thermodynamics:

Most identities in chemical thermodynamics arise from application of the first and second laws of thermodynamics, particularly the law of conservation of energy, to these state functions.

The 3 laws of thermodynamics:

  1. The energy of the universe is constant.
  2. In any spontaneous process, there is always an increase in entropy of the universe.
  3. The entropy of a perfect crystal (well ordered) at 0 Kelvin is zero.

References

1.) Ott, Bevan J.; Boerio-Goates, Juliana (2000). Chemical Thermodynamics – Principles and Applications. Academic Press.

2.) Clausius, R. (1865). The Mechanical Theory of Heat – with its Applications to the Steam Engine and to Physical Properties of Bodies. London: John van Voorst, 1 Paternoster Row. MDCCCLXVII.

3.) Klotz, I. (1950). Chemical Thermodynamics.New York: Prentice-Hall, Inc.