3.1.5 Chemical equilibria

Define reversible reaction

Products can reform to the original reactants

Define dynamic equilibrium

The reactants and products are constantly moving

What are the rates at dynamic equilibria

Rate of forward reaction is the same as rate of the backwards reaction in a closed system

What are the concentrations in dynamic equilibrium

Concentration of product and reactant is constant

Define closed system

None of reactants or products escape from reaction mixture

Define position of equilibrium

Relative amounts of products and reactants in an equilibrium mixture

What happens to concentration when equilibrium shifts left

Reactant concentration increases

What happens to concentration when equilibrium shifts right

Product concentration increases

State Le Chatelier’s Principle

“If a change is made to a system in dynamic equilibrium, position of equilibrium moves to counteract change”

What happens when concentration of reactant increases (LCP)

Equilibrium shifts to right to increase products

What happens when there’s a decrease in reactant concentration

Equilibrium shifts to left to increase reactants

What happens when temperature increases

Equilibrium moves in endothermic direction

What happens when temperature decreases

Equilibrium moves in exothermic direction

What direction is exothermic when enthalpy change is negative

forwards

What direction is exothermic when enthalpy change is positive

reverse (backwards)

What happens to equilibrium when pressure increases

Shifts to side with fewer moles of gas

What happens to equilibrium when there’s a decrease in pressure

Shifts to side with more moles of gas

What happens to equilibrium when a catalyst is present

Nothing