Equilibria - Chapter 6 and 19 Flashcards
What is a dynamic equilibrium
A continous reaction in which the forward reaction and backward reaction are proceeding at equal rates and there is no overall change in the concentration of any reactant or product
What conditions are required for equilibrium
Closed system
Reversible reaction
What factors affect the equilibrium
Concentration
Pressure
Temperature
Catalysts
What is Le Chateliers Principle
A system at equilibrium will act to oppose any change in conditions
How does concentration affect equilibrium
When more of a reactant or product are added the equilibrium shifts the opposite direction to remove excess substance
How does pressure affect equilibrium
Pressure only affect reactions with gases
When pressure is increased equilibrium shifts the direction if the side with the least moles
What affect does temperature have on equilibrium
When the temp is increased equilibrium shifts the direction of endothermic reaction
When the temp is decreased equilibrium shifts the direction of exothermic reaction
How do catalysts affect the equilibrium
They increase the rate of reaction
No change to the position of the equilibrium
What factors are considered when using reactions in industry
Yield
Time taken
Price
How is ammonia manufactured
A relatively high temp for fast reaction and relatively high yield
High pressure for high yield but costs a lot for buildings
Catalyst used for fast reaction
How is ethanol manufactured
Relatively high temperature for fast reaction and low yield
High pressure for high yield but costs a lot for buildings
Catalyst
What is Kc
The equilibrium constant
It has various units
Equation is the concentrations of the products to the power of their moles divided by the reactants
What does it mean if Kc is greater than 1
Position of equilibrium lies to the right
What does it mean if Kc is less than 1
Position of equilibrium is to the left
What if Kc is greater then 10 to the power 10
Reaction is complete
What if Kc is less than 10 to the power -10
No reaction
How are equilibrium quantities found
Use ICE
Find the change then change sign for other side, considering number of moles
Use algebra if change is unknown
What is Kp
It is an equilibrium constant used when reactions are in the gas phase to indicate the extent of a reaction at equilibrium
What is the equation for Kp
The pressure of products to the power of their moles divided by the reactants
Uses normal brackets
What units is Kp normally in
Pascal’s
What is partial pressure
It is the fraction of the total pressure caused by each individual gas
What is the equation for partial pressure
Mole fraction of gas A x total pressure
What is the equation for mole fraction of a gas
Number of moles of gas / total number of moles in mixture
What affects Kc
The value of Kc for a particular reaction is only affected by temperature changes
What does changes in the other conditions cause
They causes a shift to a new equilibrium position but the new conditions fit the same value of Kc
What affects Kp
Changes in temperature
What affects do the other factors have
Cause a new equilibrium position but the new conditions fit the same value of Kc
What does homogeneous mean
It means all the products and reactants are in the same phase/state
What is the equation for total pressure
partial pressure / mole fraction
Kp / (Kp equation)
What happens to Kp when the multiples of an equation half
You square root the Kp value
