Presentation on theme: "Approaching Equilibrium Lesson 1. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants ⇌ Products."— Presentation transcript:
Equilibrium has been attained after 40 minutes. The forward and reverse rates are equal and the reactant and product concentrations are constant.
Graph the [reactant] and [product] as equilibrium is approached. Concentration 8000 7000 6000 5000 4000 3000 2000 1000 015 30Time equilibrium
Graph the forward, reverse, & net rates as equilibrium is approached. Rate 160 140 120 100 80 60 40 20 015 30Time equilibrium
Approaching Equilibrium Reactant concentrations start high and decrease as the reaction proceeds. The forward rate, which depends on collisions of the reactants, also decreases. Product concentrations start at zero and increase as the reaction proceeds. The reverse rate, which depends on collisions of the products, also increases. Eventually the forward rate is equal to the reverse rate and the concentrations are constant. This is equilibrium.
Characteristics of a System at Equilibrium The Forward rate = The Reverse rate The Reactant and Product concentrations are constant The Macroscopic (observable) properties are constant The system is Dynamic as the forward and reverse reactions continue. The equilibrium can be approached from starting with reactants or starting with products.