Chemistry Chapter 14 - Chemical Equillibrium

Equilibrium

a process that reaches steady state

Chemical equilibrium

when a reaction reaches steady state and there are not changes to reactants or products The rate of the forward reaction and backward reaction are equal

Physical equilibrium

when physical states are at equilibrium

the equilibrium constant K

A number equal to the ratio of the equilibrium concentrations of products to the equilibrium concentrations of reactants, each raised to the power of its stoichiometric coefficient. @ a constant temp. it’s also unitless.

law of mass action

where at equilibrium the reactants and products have a specific ratio (K) at a constant temperature

The products are favored when

K > 1 ( reaction goes right )

How is homogeneous equilibrium defined?

Homogeneous equilibrium occurs when all the reactants and products in a reaction are in the same phase.

What is the difference between Kc and Kp in gas phase reactions?

Kc is the equilibrium constant expressed in terms of concentration, while Kp is expressed in terms of partial pressures.

How does the concentration of water affect equilibrium in aqueous reactions?

In aqueous reactions, the concentration of water is so high it can be considered constant and thus does not affect equillibrium

What is heterogeneous equilibrium?

Heterogeneous equilibrium occurs when the reactants and products are in different phases.

What are multiple equilibria and how is the equilibrium constant represented in such cases?

Multiple equilibria occur when a reaction involves several equilibria phases. The equilibrium constant for a multi-step reaction is the product of the equilibrium constants for each step.

What is the reaction quotient (Qc) and how is it used to determine reaction direction?

If Q < K the reaction will move to the right (make more products) If Q = K the reaction is at equilibrium If Q > K the reaction will move to the left (make more reactants)

Le Châtelier’s Principle

if a change in concentration, pressure, volume or temperature that will move a system out of equilibrium happens, then the system adjusts to reach a new equilibrium position

What impact does changing pressure and volume have on a system at equilibrium?

Increasing pressure favors the side of the reaction with fewer moles of gas; decreasing pressure favors the side with more moles of gas.

How does the equilibrium constant change with temperature for endothermic and exothermic reactions?

For endothermic reactions, the equilibrium constant increases with temperature; for exothermic reactions, it decreases.

In what way does temperature affect the equilibrium constant?

Temperature changes can affect the equilibrium constant value by altering the rates of both the forward and reverse reactions.

How is Kp related to Kc for reactions involving gases?

Kp is related to Kc by the equation Kp = Kc(RT)^∆n, where ∆n is the difference in moles of gas between products and reactants.

How do catalysts influence a reaction at equilibrium?

Catalysts provides an alternative pathway by lowerin the activation energy and speed up both the forward and reverse reactions equally, but do not change the equilibrium position.

How does changing system conditions like pressure or concentration shift equilibrium in gaseous reactions?

Changing pressure or concentration can shift the equilibrium position toward the side with fewer or more gas moles, respectively, according to Le Châtelier’s Principle.

How does dynamic equilibrium relate to chemical equilibrium?

Changing pressure or concentration can shift the equilibrium position toward the side with fewer or more gas moles, respectively, according to Le Châtelier’s Principle.