how does pressure affect the rate of gaseous reaction

Pressure affects the rate of a gaseous reaction by increasing the concentration of gas particles, which leads to a higher frequency of collisions between reactant molecules. As pressure rises, gas molecules are forced into a smaller volume, increasing their density and the likelihood of successful collisions per unit time. Consequently, this generally increases the reaction rate. However, the extent of this effect depends on the reaction's stoichiometry. For reactions where the number of gas molecules changes, increasing pressure usually speeds up the reaction and shifts the equilibrium toward the side with fewer gas molecules. For reactions where the total number of gas molecules does not change, pressure has little or no impact on the rate. Additionally, the effect of pressure on the reaction rate may be less pronounced if the activation energy is very high, as collisions may still not have enough energy to result in a reaction. In summary, increasing pressure increases the concentration of reactant gases, which typically leads to more frequent and successful collisions, thus increasing the rate of gaseous reactions, especially for those involving a change in the number of gas molecules.