<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (March 2009) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (March 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present in concentrations which have no further tendency to change with time . Usually, this state results when the forward reaction proceeds at the same rate as the reverse reaction . The reaction rates of the forward and backward reactions are generally not zero, but equal . Thus, there are no net changes in the concentrations of the reactant (s) and product (s). Such a state is known as dynamic equilibrium . </P> <P> The concept of chemical equilibrium was developed after Berthollet (1803) found that some chemical reactions are reversible . For any reaction mixture to exist at equilibrium, the rates of the forward and backward (reverse) reactions are equal . In the following chemical equation with arrows pointing both ways to indicate equilibrium, A and B are reactant chemical species, S and T are product species, and α, β, σ, and τ are the stoichiometric coefficients of the respective reactants and products: </P>

When is a system said to be in a state of dynamic chemical equilibrium
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