Equilibrium

Static Equilibrium

Two opposing forces are balanced and no change occurs

Dynamic Equilibrium

Two opposing processes are balanced and no apparent change occurs(it occurs but you just cant see it)

Equilibrium of liquids in a closed system

Rate of evaporation=rate of condensation

Characteristics of equilibrium 

Observable properties don't change over time, macroscopic properties are constant 

System is closed and temp is constant

Opposing internal processes proceed at equal rates (rxn is reversible)

What doesn't the equilibrium eqn rell us

The number of molecules or atoms present

Facts of equilibrium

Can be approached from either side of the reaction eqn

At eq’m the concentration of reactants and products don't change

Adding a catalyst doesn't affect eq’m concentrations, but eq’m is reached more quickly

When does constant K change in a rxn

Is unique to a reaction

Changing the temperature of an equilibrium reaction will change the ratio of rate constants resulting in a different equilibrium constant

What do you omit when writing k expressions

Solids and liquids

Characteristics of K

When the coefficients of an equation are changed, the value of K is raised to a power equal to the change

Ex. H2+I2→ 2HI K=50.w is turned into ½ H2+ ½ I2 → HI K= 50.2^1/2

If an equilibrium is written reversed, the the new K =1/K

What to do when adding reactions

Their equilibrium constants must be multiplied to give the K of the overall reaction

How does the system shift to accommodate an increase of pressure 

System shifts to the side with fewer gas particles to decrease pressure

How does the system shift to accommodate an decrease of pressure 

System shifts to the side with more gas particles to increase pressure

Le chateliers principles

I would like to when a change is imposed on a system in equilibrium, the system will shift in the direction which counteracts the imposed change

How does the system react when heat is added

It will counteract the heat by favoring the reaction which absorbs heat

If the temperature increases the system shifts right to use up heat

How does the system react when heat is removed

If heat is removed, it will counteract this by favoring the reaction which makes heat 

If temperature decreases, the system shifts left to release heat