Chapter 9-equilibrium Flashcards
Catalyst
Increases rate of reaction by lowering activation energy
Activation energy
Minimum energy required to break apart intermolecular bonds or reacting molecules
Chemical equilibrium
Forward and backward reactions happening at same rate-not further change in concentrations between reactants and products
Collision theory
Model for chemical reaction that states that molecules must collide with sufficient energy and proper orientation to form products
Equilibrium constant expression
Kc= [products]/[reactants] Kc= [C]^c[D]^d/[A]^a[B]^b
Where aA+bB
Equilibrium constant (Kc)
Numerical value obtained by substituting the equilibrium concentrations of the components into the equilibrium constant expression
Heterogeneous equilibrium
Equilibrium system where components are in different states
Solids and liquids are constant and equal to 1 in equations
Homogeneous equilibrium
All components in same state
Le Chatelier’s principle
When stress is placed on a system at equilibrium, the equilibrium shifts to relieve that stress
Rate of reaction
Speed at which reactants are used to form products
Rate of reaction=change in concentration of reactant or product/change in time
Temp. increase=faster
Reactant increase=faster
Reversible reaction
A reaction in which a forward reactions occurs from reactants to products and a reverse reaction occurs from products back to reactants
Concentration: add a reactant
Remove stress in direction of products (forward reaction)
Concentration: remove a reactant
Remove stress in direction of reactants (reverse reaction)
Concentration: add a product
Remove stress in direction of reactants (reverse reaction)
Concentration: remove a product
Remove stress in direction of products (forward reaction)
Volume: decrease volume
Remove stress in direction of fewer moles (smaller volume favors side with fewest gas molecules)
Volume: increase volume
Remove stress in direction of greater number of moles (larger volume favors side with most gas molecules)
Endothermic reaction (heat is reactant): raise temperature
Remove stress in direction of products (forward reaction)
Endothermic reaction (heat is reactant): lower temperature
Remove stress in direction of reactants (reverse reaction)
Exothermic reaction (heat is product): raise temperature
Remove stress in direction of reactants (forward reaction)
Exothermic reaction (heat is product): Lower temperature
Remove stress in direction of products (forward reaction)
Catalyst: increases rates equally
No effect on equilibrium
Kc>1
High ratio of products to reactants; product favored
Kc<1
Reactants favored; small ratio of products to reactants
