Final answer:
The reaction equation at constant pressure is represented by the equilibrium constant expression, which relates partial pressures of reactants and products in terms of their stoichiometric coefficients.
Step-by-step explanation:
The equation for the reaction at constant pressure, specifically in the context of gas reactions at equilibrium, is described by the equilibrium constant expression in terms of the partial pressures of the reactants and products. The general form for a reaction aA + bB → cC + dD is given by:
Kp = ((PC)c (PD)d) / ((PA)a (PB)b)
where Kp represents the equilibrium constant expressed in terms of partial pressures, PA, PB, PC, and PD are the partial pressures of the reactants and products, and a, b, c, and d are their respective stoichiometric coefficients in the balanced chemical equation. Boyle's law relates the volume and pressure for a gas at constant temperature, and Henry's law connects the pressure and solubility of a gas. In contrast, the Clausius-Clapeyron equation provides the relation between a substance's vapor pressure and temperature, but these do not directly give the expression for the equilibrium constant at constant pressure.