Equilibrium Flashcards
What is dynamic equilibrium
Both reactions occur simultaneously and at the same rate
What is a closed system
No chemicals can get in or out
When is a reaction considered to be non-reversible
If a reaction is more than 99% complete
How does the rate of forward reaction change early in equilibrium
As reactants start to be used their concentration decreases, so rate of reaction decreases
How does the rate of reverse reaction change early in equilibrium
As products are made their concentration increases, so the rate of reaction increases
What does equilibrium lying left mean
Dynamic equilibrium reached quickly when there is still lots of reactant
What does equilibrium lying right mean
Dynamic equilibrium reached slowly with lots of product
Factors that affect rate of equilibrium
Concentration
Pressure
Temperature
How does a catalyst affect an equilibrium equation
Improves rate but does not change position
What is a homogeneous system
All reactants and products in the same phase
What is a heterogeneous system
Reactants and products in at least two separate phases
What is it a reaction quotient
A mathematical relationship between the concentrations of a reaction
What is an equilibrium constant
The quotient of a reaction at equilibrium
Only applies at equilibrium
Which systems can change concentration and therefore affect equilibrium constant
Only gases and aqueous solutions can change concentration
Gases and pure liquids concentrations remain constant and are “absorbed” into Kc
What is the reaction quotient for the reaction
aA + bB becomes cC + dD
Quotient is C to the c times D to the d divided by A to the a time B to the b
What is a partial pressure
Each gas in the mixture contributes to the total pressure
The proportion of pressure due to a single gas in the mixture is it’s partial pressure
Difference in way Kc and Kp is written
Kc uses square brackets and Kp uses round brackets
Which state can have partial pressure
Gases
How to calculate partial pressure of a gas in a mixture
Partial pressure of gas A = mole fraction of A times total pressure
How to calculate mole fraction of a gas
Mole fraction of gas A = moles of A/sum of total number of gaseous moles in the mixture
What happens when Kc equals 1
The concentration of reactions and products is equal
What happens when Kc is less than 1
Equilibrium lies to the left
What happens when Kc is more than 1
Equilibrium lies to the right
How to calculate K
K = e to the power of (-delta G/RT)
Change in Kc if forward reaction is endothermic and temp increased
Increase
Change in Kc if forward reaction is endothermic and temp decreases
Decrease
Change in Kc if forward reaction is exothermic and temp increased
Decrease
Change in Kc if forward reaction is exothermic and temp decrease
Increase
