Reversible reaction

In reversible reactions, reactants (A+B) are constantly converted into products (C+D) and vice-versa. This means that the forward and backward reaction take place at the same time. The reversibility of a reaction is depicted by double arrows in a chemical equation:
General chemical reaction equation in an equilibrium state, where the reactants (A and B) are on the left side and the products (C and D) are on the right side. The equilibrium state is indicated by a double arrow.

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Article

Chemical equilibrium