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Le Châtelier's principle (1884) predicts the behavior of an equilibrium system when changes to its reaction conditions occur. 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 ...
Chemical equilibrium is a dynamic state in which forward and backward reactions proceed at such rates that the macroscopic composition of the mixture is constant. Thus, equilibrium sign ⇌ symbolizes the fact that reactions occur in both forward ⇀ {\displaystyle \rightharpoonup } and backward ↽ {\displaystyle \leftharpoondown } directions.
In chemistry, the common-ion effect refers to the decrease in solubility of an ionic precipitate by the addition to the solution of a soluble compound with an ion in common with the precipitate. [1] This behaviour is a consequence of Le Chatelier's principle for the equilibrium reaction of the ionic association / dissociation .
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. [1] When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated.
At equilibrium, the chemical force driving the forward reaction must be equal to the chemical force driving the reverse reaction. Writing the initial active masses of A,B, A' and B' as p, q, p' and q' and the dissociated active mass at equilibrium as ξ {\displaystyle \xi } , this equality is represented by
The magnitude of the equilibrium constant depends on the Gibbs free energy change for the reaction. [2] So, when the free energy change is large (more than about 30 kJ mol −1 ), the equilibrium constant is large (log K > 3) and the concentrations of the reactants at equilibrium are very small.
The extent of reaction is a useful quantity in computations with equilibrium reactions. [citation needed] Consider the reaction 2 A ⇌ B + 3 C. where the initial amounts are = , = , = , and the equilibrium amount of A is 0.5 mol. We can calculate the extent of reaction in equilibrium from its definition
The inverse recombination reaction H 3 O + + OH − → 2 H 2 O. is among the fastest chemical reactions known, with a reaction rate constant of 1.3 × 10 11 M −1 s −1 at room temperature. Such a rapid rate is characteristic of a diffusion-controlled reaction, in which the rate is limited by the speed of molecular diffusion. [15]