Eyringyhtälö

Eyringyhtälö, also known as the Eyring equation or Eyring-Polanyi equation, is a fundamental equation in chemical kinetics that relates the rate of a chemical reaction to the properties of the transition state. Developed by Henry Eyring, Michael Polanyi, and Meredith G. Evans, it provides a theoretical framework for understanding reaction rates based on thermodynamics. The equation is derived from transition-state theory, which postulates the existence of a high-energy intermediate structure called the transition state or activated complex.

The Eyring equation expresses the rate constant of a reaction in terms of the partition functions of the reactants and the transition state. It is often written in the form k = (k_B * T / h) * (Q_transition_state / Q_reactants) * exp(-ΔG‡ / RT), where k is the rate constant, k_B is the Boltzmann constant, T is the absolute temperature, h is Planck's constant, Q represents the partition function, ΔG‡ is the Gibbs free energy of activation, and R is the ideal gas constant. The term (k_B * T / h) is a universal frequency factor.

The Eyring equation is particularly useful for analyzing the temperature dependence of reaction rates and for estimating activation parameters such as activation enthalpy and activation entropy. It has wide applications in various fields of chemistry, including physical chemistry, organic chemistry, and biochemistry, for studying reaction mechanisms and predicting reaction kinetics. While it offers a powerful theoretical model, its practical application often requires approximations, especially regarding the calculation of partition functions.