Unit 3 Equilibrium Review Flashcards
Le Chateliers principle
when a stress is applied to a system in dynamic equilibrium, the equilibrium will shift to relieve the stress
exothermic
energy is a product
ΔH is negative because you lose energy
endothermic
energy is a reactant
ΔH is positive because you gain energy
dynamic equilibrium
a state of balance in a CLOSED system at constant temperature and there are no changes at the visible level but there is a constant change at the molecular level
Closed system
a reaction system in which no matter can enter or exit. Only a closed system can reach an equilibrium.
Steady State
is an open system that has no properties that are directly observable; however, this is because any materials that leave the system are immediately replaced
three stresses that can be applied to an equilibrium system
concentration
temperature
volume/pressure
concentration [ ]
NO SOLIDS
shifts away from increase
shifts toward decrease
(arrow goes towards increase. ex:
↓ → ↑
temperature
shifts away from increase
shifts toward decrease
(arrow goes towards increase. ex:
↓ → ↑)
volume/pressure
GASES ONLY
increase pressure favours side with less moles
increase volume favours side with more moles
catalysts
catalyst is a substance that speeds
up the rate of reaction without being used up in the reaction.
*Catalysts will NOT have any effèct on an equilibrium position because they speed up the reaction equally in both directions.
concentration graph
vertical line and a hill
temperature graph
all hills
pressure graph
all vertical lines
keq
[products]/[reactants]
keq is only
gases and aqueous
no solids or liquids
if keq is larger than 1
A value for Keq significantly.
larger than one means that products are favored over reactants.
if keq is less than one
A value of Keq significantly less than one it means that reactants are favoured over products
if keq is very close to 1
A value of Keq very close to 1 means that the (reactant] ~ [product)
spontaneous
products are favoured
large equilibrium constant (keq)
> > > > > 1
non spontaneous
reactants are favoured
small equilibrium constant
««1
ICE charts
Initial: if not known, put 0
Change: + or - ___x (one side will be +, one side will be -) (__x will be the # in front of chemical)
Equilibrium: if not given is I + C
dissociation
is reversible physical change
net ionic
the non reversible chemical change where an insoluble ppt is formed
solubility
the mass of a given substance that can be dissolved by a specific solvent at a given temp
saturated solution
the solvent has the maximum amount of solute dissolved in it can hold at that specific temp
ON the line
unsaturated solution
the solvent can still dissolve more solute at that temperature
UNDER the line
supersaturated solution
a solvent can hold more than the maximum amount of solute at a given temp
ABOVE the line
equilibrium
balanced state of a reversible reaction in which there is NO observable change
the rate of the forward reactor equals that of the reverse reaction
Le Chateliers principle pt 2
if a system at equilibrium is subjected to an external stress, the equilibrium will shift so as to minimize that stress
in heat, equilibrium will shift…
in the case of heat, the equilibrium will shift in the direction which the added heat is used up
what happens to the solubility of solids when you increase temperature
when you increase the temperature of a solid, the solubility increases
solids are endothermic
what happens to the solubility of gases when you increase temperature
the solubility decreases upon heating
exothermic
common ion effect
the solubility of an ionic substance in water is decreased when another substance containing ONE of the ions in the solution (the common ion) is added
predicting precipitate’s:
if Qsp is larger than Ksp
a precipitate WILL form
predicting precipitate’s:
if Qsp is smaller than Ksp
a precipitate will NOT form
the solution is unsaturated
predicting precipitate’s:
if Qsp is equal to Ksp
the solution is saturated and no change will occur
when it gives you solubility
calculate ksp
when it gives you ksp
find solubility by substituting x for the chemicals
ksp
only products
