10-11. Equilibrium I and II Flashcards
what is a reversible reaction
a reaction that goes both ways
what is dynamic equilibrium
when the rate of the forwards reaction is the same as the rate of the backwards reaction
what remains constant at dynamic equilibrium
concentrations of reactants and products
what type of system does dynamic equilibrium occur in
closed system
what is a homogenous system
all reactants and products are in the same physical state
what is Kc
the equilibrium constant involving concentrations
aA + bB = dD + eE
Kc = [D]^d [E]^e / [A]^a [B]^b
what is a heterogenous system
not all reactants and products are in the same physical state
what state is included in Kc and why
only gases as their concentrations remain constant
are catalysts included
catalysts are not included as they are not used up, they only speed up the rate at which dynamic equilibrium is reached
what is le Chatelier’s principle
if there is a change in concentration, pressure or temperature, the equilibrium will shift to counteract the change
what happens when you change concentration, pressure of temperature of a reversible reaction
you alter the position of equilibrium and end up with different amounts of reactants and products at equilibrium
what do you get when the position of equilibrium moves left
more reactants
what do you get when the position of equilibrium moves right
more products
le chatelier’s principle for increasing concentration of reactants
makes more product - equilibrium shifts right
le chatelier’s principle for increasing concentration of product
makes more reactants - equilibrium shifts left
le chatelier’s principle for decreasing concentration of reactants
makes more reactants - equilibrium shifts left
le chatelier’s principle for decreasing concentration of products
makes more products - equilibrium shifts right
le chatelier’s principle for increasing pressure
equilibrium shifts to the side with fewer gas molecules
(look at number of moles on each side)
le chatelier’s principle for decreasing pressure
equilibrium shifts to side with more gas molecules ( look at number of moles on each side)
le chatelier’s principle for increasing temperature
equilibrium shirts to the endothermic direction to absorb the heat
le chatelier’s principle for decreasing temperature
equilibrium shifts to the exothermic direction to replace the heat
if a forward reaction is endothermic what is the reverse reaction
exothermic
how to find the equilibrium constant from experimental data
Fe2+ + Ag+ -><- Fe3+ + Ag
1. leave iron sulfate solution and silver nitrate solution in stoppered flask at 298k, reaction will reach equilibrium
2. take samples and titrate them to work out c of Fe2+ ions
3. from this work our equilibrium concentrations of other components and then work out Kc
what is partial pressure
the individual pressure of each gas in a mixture
what is total pressure
the sum of all the partial pressures of individual gases in a mixture
equation for mole fraction
mole fraction = number of moles of gas / total moles of a gas in a mixture
partial pressure equation
partial pressure = mole fraction of gas / total pressure
what is Kp
equilibrium constant involving pressure
Kp equation
p(D)^d p(E)^e / p(A)^a p(B)^b
the greater value of Kc or Kp …..
the further right the equilibrium lies
the smaller value of Kc or Kp……
the further left the equilibrium lies
why do Kc or Kp not change
as the reaction shifts to keep the equilibrium constants constant
