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If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to partially reverse the change. For example, adding more S (to the chemical reaction above) from the outside will cause an excess of products, and the system will try to counteract this by increasing the reverse reaction and pushing the ...
A simple example occurs with acid-base equilibrium such as the dissociation of acetic acid, ... the equilibrium constant for the reaction is defined as = [] [] ...
The equilibrium constant for a full redox reaction can be obtained from the standard redox potentials of the constituent half-reactions. At equilibrium the potential for the two half-reactions must be equal to each other and, of course, the number of electrons exchanged must be the same in the two half reactions.
For example, consider the Haber process for the synthesis of ammonia (NH 3): N 2 + 3 H 2 ⇌ 2 NH 3. In the above reaction, iron (Fe) and molybdenum (Mo) will function as catalysts if present. They will accelerate any reactions, but they do not affect the state of the equilibrium.
the reaction results in the change of the number of moles of gas in the system. In the example reaction above, the number of moles changes from 4 to 2, and an increase of pressure by system compression will result in appreciably more ammonia in the equilibrium mixture. In the general case of a gaseous reaction: α A + β B ⇌ σ S + τ T
In a reversible reaction, chemical equilibrium is reached when the rates of the forward and reverse reactions are equal (the principle of dynamic equilibrium) and the concentrations of the reactants and products no longer change. This is demonstrated by, for example, the Haber–Bosch process for combining nitrogen and hydrogen to produce ammonia.
Weak acids and bases undergo reversible reactions. For example, carbonic acid: H 2 CO 3 (l) + H 2 O (l) ⇌ HCO 3 − (aq) + H 3 O + (aq). The concentrations of reactants and products in an equilibrium mixture are determined by the analytical concentrations of the reagents (A and B or C and D) and the equilibrium constant, K.
Equilibrium constant, a quantity characterizing a chemical equilibrium in a chemical reaction; Partition equilibrium, a type of chromatography that is typically used in GC; Quasistatic equilibrium, the quasi-balanced state of a thermodynamic system near to equilibrium in some sense or degree; Schlenk equilibrium, a chemical equilibrium named ...