Chapter 19 - Equilibrium Flashcards
The equilibrium constant - part 2, The equilibrium constant, Controlling the position of equilibrium.
How are the units of Kc worked out?
Substitute units into the expression
Cancel common units
What is a homogeneous equilibrium?
Equilibrium species all have the same state.
What is a heterogeneous equilibrium?
Equilibrium species that have different states.
In a heterogeneous equilibrium, what is discounted in the expression for Kc?
Any species that are not as a gas or in solution.
What is a mole fraction?
The proportion of the volume of a gas to the total volume of gases in the mixture.
What is the partial pressure?
The contribution that the gas makes towards the total pressure P.
How is a mole fraction calculated?
Mole fraction χ(A) = n(A)/n(total)
How is partial pressure calculated?
p(A) = mole fraction x total pressure P p(A) = χ(A) x P
What is the way to check the partial pressures are correct?
Sum of the partial pressures equals the total pressure.
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))
What does the magnitude of an equilibrium constant represent?
The extent of an equilibrium
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
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
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 effect does increasing pressure have on a reaction with fewer moles of gaseous products than reactants?
Products increase
Reactants decrease
Equilibrium shifts to right
