equilibrium constant Flashcards
what is Kᴄ
The equilibrium constant
Define homogeneous equilibria
All the species of the equilibira have the same phase/ state
Define hetrogeneous equilibria
The species of equilibria have different phases/states
Some states left out of Kᴄ and Kᴘ equilibria, what states and why?
Species with solid and liquid states are left out of calculations as their concentrations are constant.
What is Kᴘ
The equilibrium constant for partial pressures.
Why does Kᴘ have a direct relatioship to Kᴄ?
Concentration and partial pressues are proportional.
What is the equation for molar fraction?
Molar fraction =
Number of moles of ‘x’ /
total number of moles in gas mixture
what is the equation for partial pressure
Partial pressure =
Molar fraction X total pressure
What is the only condition that will cause the equilibrium constant to change?
Temperature
Name two conditionas that do not cause a change in the equilibrium constant
Any two from:
- Concentration
- Pressure
- Catalyst
If the forward reaction is exothermic what happens to the equilibrium constant if temperature increases?
The equilibrium constant will decrease, and shift towards the reactants.
Describe what happens to the Kᴄ or Kᴘ value of an (exothermic forward) reaction when the temperature increases
A new Kᴄ or Kᴘ value is made (smaller than before), an the system is therefore no longer in equilibrium. The product’s partial pressure or concentration must decrease and the reactants concentration or pressure must increase until the new Kᴄ or Kᴘ values are met. The system will then be in the new equilibrium.
Describe what happens to the Kᴄ or Kᴘ value of an (endothermic forward) reaction when the temperature increases
A new Kᴄ or Kᴘ value is made (Larger than before), an the system is therefore no longer in equilibrium. The product’s partial pressure or concentration must increase and the reactants concentration or pressure must decrease until the new Kᴄ or Kᴘ values are met. The system will then be in the new equilibrium.
If the forward reaction is endothermic and the temperature increases what happens the the equilibrium constant?
The equilibrium constants increase.
What affects equilibrium positions and what affects equilibrium constants?
Positions:
- Concentration
- Pressure
- Temperature.
Constants:
- Temperature
N₂O₄ ⇌ 2NO₂
What occurs when the concentration of N₂O₄ is increased?
The system is no longer in equilibrium, and the Kᴄ value will of decreased, (which cannot occur), the concentration of N₂O₄ must decrease, and 2NO₂ conc must increase, to return the system to the origional Kᴄ value, a new equilibrium position is made shifted to the right.
N₂O₄ ⇌ 2NO₂
What occurs when the pressure is increased?
If the pressure is increased the Kᴘ value will increase, (which cannot occur), the partial pressure of 2NO₂ must decrease and increase for N₂O₄. This returns the system to the origional Kᴘ value, a new position of equilibrium is made shifted to the left.
