EQUILIBRIUM Equilibrium Occurs when in a reaction the
EQUILIBRIUM
Equilibrium • Occurs when, in a reaction the reactant form products AND products reform reactants at the same rate • Equilibrium is symbolized by using a double headed arrow in the chemical equation (⇄)
CO(g) + H 2 O(g) ⇄ CO 2(g) + H 2(g) [CO] or [H 2 O] Concentration [CO 2] or [H 2] Time Equilibrium
• The blue line shows the reactants being used up • The red line shows the products being produced • At the dotted line, equilibrium is achieved • At equilibrium, the reaction “stops” • The forward and reverse reactions are occurring at the same rate
Equilibrium Constant • For the reaction: x. REACTANTS ⇄ y. PRODUCTS • [ ] means “concentration (in molarity) of”
Example • Construct the equilibrium constant for the reaction below: 2 A + 3 B ⇄ C
• Solids and Liquids do not appear in the equilibrium constant expression. • Only gases and dissolved substances (aqueous) appear in the expression.
• Construct the equilibrium constant expression for the below reaction at equilibrium: 2 A(s) + 3 B(g) ⇄ C(g)
Interpreting Keq • If Keq > 1, then the reaction favors more product formation • Favored to the right • If Keq < 1, then the reaction favors more reactant formation • Favored to the left
Relationship to Acids/Bases • Weak acids/bases have a Keq value that can be calculated. • Strong acids/bases have a Keq that is infinitely large. They dissociate completely leaving no reactant in solution.
- Slides: 10