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 basis of good manners is self-reliance. Necessity is the law of all who are not self-possessed.”
—Ralph Waldo Emerson (1803–1882)
“Law without education is a dead letter. With education the needed law follows without effort and, of course, with power to execute itself; indeed, it seems to execute itself.”
—Rutherford Birchard Hayes (1822–1893)
“When over Catholics the ocean rolls,
They must wait several weeks before a mass
Takes off one peck of purgatorial coals,
Because, till people know what’s come to pass,
They won’t lay out their money on the dead—
It costs three francs for every mass that’s said.”
—George Gordon Noel Byron (1788–1824)
“You are, I am sure, aware that genuine popular support in the United States is required to carry out any Government policy, foreign or domestic. The American people make up their own minds and no governmental action can change it.”
—Franklin D. Roosevelt (1882–1945)