Consider the reaction H₂(g) + I₂(g) → 2 HI(g). The reaction of a fixed amount of H₂ and I₂ is studied in a cylinder fitted with a movable piston. Indicate the effect of each of the following changes on the rate of the reaction. (b) An increase in volume at constant temperature

Key Concepts

Reaction Rate

The reaction rate refers to the speed at which reactants are converted into products in a chemical reaction. It is influenced by several factors, including concentration, temperature, and the presence of catalysts. In gas-phase reactions, the concentration of reactants can be affected by changes in volume, which in turn impacts the frequency of collisions between molecules.

Ideal Gas Law

The Ideal Gas Law (PV = nRT) describes the relationship between pressure (P), volume (V), temperature (T), and the number of moles (n) of a gas. When the volume of a gas increases at constant temperature, the pressure decreases, which can lead to a change in the concentration of the gaseous reactants. Understanding this law is crucial for predicting how changes in volume affect reaction rates.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. In the context of the reaction H2(g) + I2(g) → 2 HI(g), increasing the volume decreases the concentration of the reactants, which can shift the equilibrium position and potentially affect the rate of the forward reaction.