In Chemistry, the law of mass action is a mathematical model that explains and predicts behaviors of solutions in dynamic equilibrium. It can be described with two aspects: 1) the equilibrium aspect, concerning the composition of a reaction mixture at equilibrium and 2) the kinetic aspect concerning the rate equations for elementary reactions. Both aspects stem from the research by Cato M. Guldberg and Peter Waage between 1864 and 1879 in which equilibrium constants were derived by using kinetic data and the rate equation which they had proposed. Guldberg and Waage also recognized that chemical equilibrium is a dynamic process in which rates of reaction for the forward and backward reactions must be equal.
Taken as a statement about kinetics, the law states that the rate of an elementary reaction (a reaction that proceeds through only one transition state, that is one mechanistic step) is proportional to the product of the concentrations of the participating molecules. In modern chemistry this is derived using statistical mechanics.
Taken as a statement about equilibrium, that law gives an expression for the equilibrium constant, a quantity characterizing chemical equilibrium. In modern chemistry this is derived using equilibrium thermodynamics.
Read more about Law Of Mass Action: History, Contemporary View
Famous quotes containing the words law of, law, mass and/or action:
“The law of God is a law of change, and ... when the Churches set themselves against change as such, they are setting themselves against the law of God.”
—George Bernard Shaw (1856–1950)
“Who does not know history’s first law to be that an author must not dare to tell anything but the truth? And its second that he must make bold to tell the whole truth? That there must be no suggestion of partiality anywhere in his writings? Nor of malice?”
—Marcus Tullius Cicero (106–43 B.C.)
“Masterpieces are not single and solitary births; they are the outcome of many years of thinking in common, of thinking by the body of the people, so that the experience of the mass is behind the single voice.”
—Virginia Woolf (1882–1941)
“Though with their high wrongs I am struck to the quick,
Yet with my nobler reason ‘gainst my fury
Do I take part. The rarer action is
In virtue than in vengeance.”
—William Shakespeare (1564–1616)