5.2 Equilibrium Flashcards
What is the Kc equation ?
Kc = [products]^x / [reactants]^y
What is a homogeneous equilibria ?
Contains equilibrium species that all have the same state or phase.
What is heterogenous equilibria ?
Contains equilibrium species that have different states or phases.
What is mole fraction ?
The mole fraction is the same as its proportion by volume to the total volume of gases in a gas mixture. Sum of mole fractions must equal 1.
How do you work out mole fraction ?
For gas A
x(A) = number of moles of A / total number of moles.
What is partial pressure ?
The gas contribution that the gas makes towards the total pressure. The sum of the partial pressures of each gas equals the total pressure.
How do you work out partial pressure ?
For gas A:
p(A) = mole fraction of A x total pressure
What is the equilibrium constant, Kp ?
Similar to Kc but with the partial pressures replacing concentration terms.
Kp = p(products)^x / p(reactants)^y
What indicates the extent of a chemical equilibrium ?
The magnitude of an equilibrium.
What does a K value of 1 indicate ?
Indicates an equilibrium halfway between reactants and products.
What does a K value of 100 indicate ?
Indicates an equilibrium well in favour of the products.
What does a K value of 1x10-2 indicate ?
Indicates an equilibrium well in favour of the reactants.
What affects the value of K ?
K gives the exact equilibrium position. At a set temperature, K is constant, but as the temperature changes so does K. Concentration and pressure do not affect value of K.
What occurs to the equilibrium constant in exothermic reactions ?
If the forward reaction is exothermic, the equilibrium constant decreases with increasing temperature. Raising the temperature decreases the equilibrium yield of products.
What occurs to the equilibrium constant in endothermic reactions ?
If the forward reaction is endothermic, the equilibrium constant increases with increasing temperature. Raising the temperature increases the equilibrium yield of products.
