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How can reaction products revert to reactants in a reversible reaction?

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dissociation of E–N — reaction mechanism Possible energy diagram for the dissociation of a covalent molecule, E–N, into its ions E⁺ and N⁻ (see text).

In a reversible chemical reaction, products can revert to reactants because the reaction is capable of proceeding in either direction depending on the conditions.12

At the microscopic level, this process is governed by the principle of microscopic reversibility, which states that the pathway taken by the reverse reaction is statistically identical to that of the forward reaction. When a system reaches chemical equilibrium, the forward and reverse reactions occur at equal rates, resulting in no net change in the concentrations of substances, even though continuous molecular activity persists.342

Several factors influence this reversal:
* Concentration: If the position of equilibrium is unfavorable, the accumulation of products can drive the reaction back toward the reactants. Conversely, changing the concentration of reagents can shift the equilibrium according to Le Chatelier's principle.52
* Energy Barriers: Molecules must overcome an activation energy barrier to react. From the transition state, molecules may lose energy through collisions and revert to starting materials rather than proceeding to products.46
* Conditions: Variables such as temperature and pressure can alter the rates of the forward and reverse reactions, thereby shifting the equilibrium position.27