equilibrium constants + reaction quotients , Equilibrium Constant Expression and Equilibrium Constant

What does "Q" represent?

reaction quotient: a value that represents the mass action expression of a reversible chemical reaction, can be used when reaction is not at equilibrium

When will Q=K?

When the reaction is at equilibrium.

When is Q>K?

when the reaction shifts left (the product's [ ] was too large, the reaction wants to make more reactants -> equilibrium.)

When is Q<K?

when the reaction shifts right (the reactant's [ ] was too large, reaction wants to go to equilibrium.)

How do you calculate Q?

Q=[products]/[reactants]

What factors change the equilibrium position?

concentration, pressure, temperature

How does increasing temperature (exothermic) affect the equilibrium position?

the reaction shifts left
reactants <> products + heat

How does decreasing temperature (endothermic) affect the equilibrium position?

the reaction shifts right
reactants + heat <> products

How does increasing the pressure of an equilibrium reaction mixture affect the reaction?

It would shift towards the side of the reaction with fewer moles of gas

How does decreasing the pressure of an equilibrium reaction mixture affect the reaction?

It shifts towards the side of the reaction with more moles of gas.

What does ICE stand for in ICE tables?

Initial, Change, Equilibrium

What is the equilibrium constant expression?

Kc = [products]/[reactants]

How do you calculate Kp?

partial pressures of products/reactants (all to the power of their coefficient)

How do you calculate △n?

△n = # moles products - #moles reactants

Equilibrium

When the forward and reverse reaction rates are equivalent

Equilibrium constant expression

Written with products multiplied together and raised to the power of their stoichiometric coefficients divided by the reactants multiplied together raised to their stoichiometric coefficients

Equilibrium constant (K)

The value of the equilibrium constant expression

Dynamic equilibrium

Equilibrium where both the forward and reverse reactions are occurring but there is no net change in chemical concentrations

Kc

Equilibrium constant expression using concentration values (molarity)

Kp

Equilibrium constant expression using pressure values (atm)

Le Chatelier's Principle

A system at equilibrium will shift in the direction to oppose the stress on the system

Factors affecting equilibrium: Concentration

Changing concentrations of chemicals in the equilibrium expression

Factors affecting equilibrium: Pressure

Changing the pressure by changing the volume of a system

Factors affecting equilibrium: Temperature

Heating or cooling a system

Factors affecting equilibrium: Add Solvent

Shifting a reaction by changing the chemical concentrations as the solvent is added

K reverse

The equilibrium constant for the reverse reaction is the reciprocal of the equilibrium constant for the forward reaction

K multiply

The equilibrium constant for a reaction multiplied by a constant is raised to the power of that constant

K add

The equilibrium constant for the sum of two reactions is the product of the equilibrium constants for the individual reactions

Kc for reversed reaction

The equilibrium constant for a reversed reaction is the reciprocal of the equilibrium constant for the original reaction

Kc for multiplied reaction

The equilibrium constant for a reaction multiplied by a constant is raised to the power of that constant

Kc for added reactions

The equilibrium constant for the sum of two reactions is the product of the equilibrium constants for the individual reactions