Equilibria Flashcards
How does temperature impact Kc/Kp for exothermic reactions?
For exothermic reactions:
Increase in temperature = Kc decreases
Decrease in temperature = Kc increases
How does temperature impact Kc/Kp for endothermic reactions?
For endothermic reactions:
Increase in temperature = Kc increases
Decrease in temperature = Kc decreases
What is the definition of dynamic equilibrium?
Where the rate of the forward and backwards reaction is the same, so the concentration of the reactants and products is constant
Where can dynamic equilibria be reached?
Only in closed systems (i.e. nothing being added or leaving)
What do you need to watch out for when finding the Kc of heterogenous reactions?
Solids and pure liquids should not be put into the Kc equation, as their concentrations are constant. Only add aqueous and gas species
What is total pressure of a reaction?
All the partial pressures added together
What does partial pressure equal in terms of mole fractions?
Mole fraction of a gas x Total pressure = Partial pressure
How do you work out the mole fraction of a gas?
Number of moles of the gas / Total number of moles of gas in the mixture
What is included in Kp expressions?
The partial pressures of products / The partial pressures of reactions (must all the be gases AT EQUILIBRIUM)
What is the impact of changes in pressure on the value of Kp?
Pressure has no effect on the value of Kp
What is the impact of a catalyst on the value of Kp?
Catalysts have no impact on the value of Kp, but rather speeds up the rate at which equilibrium is reached
If the temperature changes forces equilibrium to shift to the right, what happens to the value of Kp/Kc?
The value of Kp/Kc increases
If the temperature changes forces equilibrium to shift to the left, what happens to the value of Kp/Kc?
The value of Kp decreases
What is the impact of changes in concentration on the value of Kc?
Changes in concentration have no impact on the value of Kc, as Kc is at equilibrium only, where the concentration of reactants and products is constant
What is Qc?
Qc is essentially the same as Kc but can be found at any value, not just at equilibrium
What is Qc as known as?
Reaction quotient
How can you use Qc to help predict how a reaction will proceed and adjust to reach equilibrium?
You can compare the value of Qc to Kc.
For example Qc>Kc this indicated that the amount of product currently present (at Qc) is more than there would be at equilibrium (Kc), so you can predict that on the journey to equilibrium the reaction rid of some of the product.
What does it mean if Qc=Kc?
The reaction is already at equilibrium
