HESI A2 Science Practice Test 2025 - Free Practice Questions and Study Guide

In a chemical equilibrium context, an irreversible reaction is characterized by the reactants converting into products to nearly completion, resulting in the formation of products that do not readily revert back to reactants under normal conditions. In such reactions, the forward reaction proceeds to a point where the reactants are mostly consumed. This leads to a significant predominance of products, achieving a state of near-complete conversion.

This contrasts with reversible reactions, where both reactants and products can convert back and forth, resulting in a balance between them. Endergonic and exergonic refer to the energy changes associated with the reactions but do not specifically address the completeness of reactant conversion to products or the nature of equilibrium. In summary, an irreversible reaction effectively utilizes almost all of the reactants, aligning perfectly with the question's premise regarding a state of chemical equilibrium.