Equilibria Flashcards
Homogeneous equilibria
All reactants and products in the same state
Heterogeneous equilibria
Products and reactants in mixed states (only use gaseous states in Kc calculation
Kc calculation
[HA] / [A-] [H+]
Mole fraction
The same as its proportion by volume to the total volume of gases in a gas mixture
Mole fraction calculation
Number of miles of A/ total number of miles in gas mixture
Partial pressure
The contribution that the gas makes towards the total pressure p. The some of the partial pressures is equal to the total pressure
Partial pressure calculation
Mole fraction of A x total pressure p
Kp calculation
p(HA) / p(A-) p(H+)
K= 1
Indicates an equilibrium halfway between reactants and products
K= 100
Indicates an equilibrium well in favour of the products
K= 1x10^-2
Indicates an equilibrium well in favour of the reactants
When does K change?
If the temperature changes
What doesn’t effect K?
Concentration
Pressure
Presence of a catalyst
Le chateliers principle
1) if concentration increases, equilibrium shifts to reduce that increase.
2) if pressure increases, equilibrium shifts towards the side with fewer gaseous moles
3) if temperature increases, equilibrium shifts in the endothermic direction
Ectothermic reaction
Gives out energy
Endothermic reactions
Takes in energy
Increasing temperature in exothermic reactions
- equilibrium constant decreases
- decreases equilibrium yield of product
- equilibrium shifts left
Effect of increasing temperature in Endothermic reaction
- equilibrium constant increases
- increases equilibrium yield of products
- equilibrium position shifts right
What effect do catalysts have?
- Affect the rate of a chemical reaction but not the position of equilibrium.
- speed up both the forward and reverse reactions by the same factor
- equilibrium is reached faster but position is the same
How the concentration changes to return the ratio back to the Kc value
If the concentration of product increases, the concentration of reactant decreases.
= equilibrium shifts right
Doubling the pressure of the products and reactants in an equilibrium
Double pressure= double of partial pressures and concentrations of both.
Partial pressure of products must decrease and of reactants must increase.
=Equilibrium shifts left
