Chemical Equilibrium - Types of Equilibrium

Types of Equilibrium

1. In the gas phase. Rocket engines
2. The industrial synthesis such as ammonia in the Haber-Bosch process (depicted right) takes place through a succession of equilibrium steps including adsorption processes.
3. atmospheric chemistry
4. Seawater and other natural waters: Chemical oceanography
5. Distribution between two phases
   1. LogD-Distribution coefficient: Important for pharmaceuticals where lipophilicity is a significant property of a drug
   2. Liquid-liquid extraction, Ion exchange, Chromatography
   3. Solubility product
   4. Uptake and release of oxygen by haemoglobin in blood
6. Acid/base equilibria: Acid dissociation constant, hydrolysis, buffer solutions, indicators, acid-base homeostasis
7. Metal-ligand complexation: sequestering agents, chelation therapy, MRI contrast reagents, Schlenk equilibrium
8. Adduct formation: Host-guest chemistry, supramolecular chemistry, molecular recognition, dinitrogen tetroxide
9. In certain oscillating reactions, the approach to equilibrium is not asymptotically but in the form of a damped oscillation .
10. The related Nernst equation in electrochemistry gives the difference in electrode potential as a function of redox concentrations.
11. When molecules on each side of the equilibrium are able to further react irreversibly in secondary reactions, the final product ratio is determined according to the Curtin-Hammett principle.

In these applications, terms such as stability constant, formation constant, binding constant, affinity constant, association/dissociation constant are used. In biochemistry, it is common to give units for binding constants, which serve to define the concentration units used when the constant’s value was determined.