M5 - Equilibrium (how far?) Flashcards
B
what is Kp?
Kp is the equilibrium constant using gases.
How is partial pressure calculated?
p(A) = mole fraction x total pressure P p(A) = χ(A) x P
What effect does increasing pressure have on a reaction with the same number of moles of gaseous products and reactants?
No change
Equilibrium stays the same
What is a homogeneous equilibrium?
in homogeneous equilibrium all Equilibrium species all have the same state.
N2(g) + 3H2 (g) = 2NH3 (g)
all species in this example are gas
B
B
What is the effect of a catalyst on the equilibrium constant?
Catalysts affect the rate but not the equilibrium position.
Equilibrium is reached faster but position does not change.
What effect does increasing pressure have on a reaction with fewer moles of gaseous products than reactants?
Products increase
so Reactants decrease
so Equilibrium shifts to right
What is the formula to calculate the partial pressure for gas equilibria? (1)
Partial Pressure p(A) = mole fraction of A x total pressure P (1)
What would K=1, K=100 and K=0.01 represent?
K=1: equilibrium halfway between reactants and products
K=100: equilibrium in favour of products
K=0.01: equilibrium in favour of reactants
Write a Kp expression for this equilibrium reaction
What does the magnitude of an equilibrium constant represent?
The extent of an equilibrium
What is a heterogeneous equilibrium?
In heterogeneous equilibrium Equilibrium species that have different states.
C(s) + H2O (g) = CO(g) + H2(g)
Write a Kc expression for this equilibrium reaction
What is the formula to calculate the mole fraction for gas equilibria? (1)
Mole fraction x(A) = number of moles of A / total number of moles in a gas mixture (1)
What is the way to check the partial pressures are correct?
Sum of the partial pressures equals the total pressure.
What is the partial pressure?
The contribution that the gas makes towards the total pressure P.
In a heterogeneous equilibrium, what is discounted in the expression for Kc?
Any species that are not a gas or in solution (aqueous) .
so solids and liquids are ommited
What is a mole fraction?
The proportion of the volume of a gas to the total volume of gases in the mixture.
What effect does increasing pressure have on a reaction with more moles of gaseous products than reactants?
Products decrease
Reactants increase
Equilibrium shifts to left
D
What is the effect on K when the temperature is increased and the forward reaction is endothermic?
Equilibrium constant increases
Equilibrium shifts to product side
What is the effect on K when the temperature is increased and the forward reaction is exothermic?
Equilibrium constant decreases
Equilibrium shifts to reactant side
mole fraction equation?
Mole fraction χ(A) = n(A)/n(total)
B
How are the units of Kc worked out?
Substitute units into the expression
Cancel common units
B
With the equilibrium H(2) + I(2) = 2HI, what is the expression for Kp?
Kp = p(HI)^2 / p(H(2)) x p(I(2))
