mass-law effect

https://doi.org/10.1351/goldbook.M03725
At equilibrium, the product of the activities (or concentrations) of the reacting species is constant. Thus for the equilibrium: \[\alpha\,\text{A}\,+\,\beta\,\text{B}\rightleftharpoons \gamma\,\text{C}\,+\,\delta\,\text{D}\] \[K=\frac{\left[\text{C}\right]^{\gamma }\ \left[\text{D}\right]^{\delta }}{\left[\text{A}\right]^{\alpha }\ \left[\text{B}\right]^{\beta }}\]
See also:
common-ion effect
,
equilibrium
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1138 [Terms] [Paper]