Equilibrium Systems

NO2(g) → N2O4(g) Chemical equilibrium – the state of a reaction in which all reactants and products have reached constant concentrations in a closed system

Dynamic Equilibrium Dynamic equilibrium – is a balance between forward and reverse processes that are occurring simultaneously at equal rates.

Dynamic Equilibrium

H2O(g) + CO(g) → H2(g) + CO2(g) Equilibrium Position – the relative concentration of reactants and products in a system in dynamic equilibrium H2O(g) + CO(g) → H2(g) + CO2(g)

H2O(g) + CO(g) ⇌ H2(g) + CO2(g) Reversible reaction– a chemical reaction that proceeds in both the forward and reverse directions, setting up an equilibrium in a closed system H2O(g) + CO(g) ⇌ H2(g) + CO2(g) ⇌ is a symbol that represents a reaction that can go in both directions (ie a reversible reaction)

Equilibrium can be reached in either direction 2NO2(g) → N2O4(g) N2O4(g) →2NO2(g) N2O4(g) ⇌ 2NO2(g) Starting with either gas resulted in the same equilibrium concentrations.

For a closed chemical equilibrium system in constant environmental conditions, the same equilibrium concentrations are reached regardless of the direction by which equilibrium was reached

Stoichiometry and Chemical Equilibria Consider the following reaction: N2(g) + 3H2(g) ⇌ 2NH3(g) The molar ratio (1:3:2) predicts the changes in concentration. IE for every mole of N2 consumed 3 H2 are consumed & 2NH3 produced. This principle can be used to determine concentrations for chemical equilibria.

Initial, Change, Equilibrium Table ICE Table [H2]initial=2.00 M [F2]initial=2.00 M [HF]initial=0 [F2]equilibrium=0.48 M Find the equilibrium []’s of H2 & HF

V=2.0L Find the equilibrium []’s of N2 & H2