“Equilibrium” What does it mean? What word does it look like? What does it mean? What word does it look like?
Post on 17-Dec-2015
226 Views
Preview:
Transcript
“Equilibrium”“Equilibrium”
What does it mean? What word does it look like?
What does it mean? What word does it look like?
Aim: How can we look at systems at equilibrium?
Aim: How can we look at systems at equilibrium?
Equilibrium: a state of balance
Dynamic Equilibrium: when overall rates of forward and reverse reactions are equal
This is a Reversible Equilibrium and is indicated by a double arrow
Equilibrium: a state of balance
Dynamic Equilibrium: when overall rates of forward and reverse reactions are equal
This is a Reversible Equilibrium and is indicated by a double arrow
Physical EquilibriumPhysical Equilibrium
Physical Equilibrium is balance in physical processes
Phase equilibrium: equilibrium between phases
Physical Equilibrium is balance in physical processes
Phase equilibrium: equilibrium between phases
Solution EquilibriumSolution Equilibrium
Solution Equilibrium: dissolving & crystallization happening at equal rate
Solution Equilibrium: dissolving & crystallization happening at equal rate
liquid-gasliquid-solid
Chemical EquilibriumChemical Equilibrium
CH4 (g) + H2O (g) 3 H2 (g) + CO (g) CH4 (g) + H2O (g) 3 H2 (g) + CO (g)
Chemical EquilibriumChemical Equilibrium
CH4 (g) + H2O (g) 3 H2 (g) + CO (g) CH4 (g) + H2O (g) 3 H2 (g) + CO (g)
HomeworkHomework
Finish equilibrium review pages Finish equilibrium review pages
Remember: Equilibrium is StabilityRemember: Equilibrium is Stability
CH4 + H2O 3 H2 + CO
Fwd rxn rate = Rev Rxn rate Using up reactants to make products
CH4 + H2O 3 H2 + CO
Fwd rxn rate = Rev Rxn rate Using up reactants to make products
How will a closed system react when a stress if applied?
How will a closed system react when a stress if applied?
equilibrium
stress
new equilibrium
Le Chatelier’s PrincipleLe Chatelier’s Principle
Closed systems will adjust to balance stresses Concentration, temperature, pressure
Shifts are increased reaction rates in either Fwd (right→) or Rev (left←) directions
Closed systems will adjust to balance stresses Concentration, temperature, pressure
Shifts are increased reaction rates in either Fwd (right→) or Rev (left←) directions
ConcentrationConcentration
Pen/pencil trick, pointing towards shift
A + B C
Add-Away, Take-Towards
Pen/pencil trick, pointing towards shift
A + B C
Add-Away, Take-Towards
https://www.youtube.com/watch?v=7zuUV455zFs
https://www.youtube.com/watch?v=7zuUV455zFs
ConcentrationConcentration Add-Away Add-Away
ConcentrationConcentration Take-Towards Take-Towards
Le Chatelier’s Principle:Temperature
Le Chatelier’s Principle:Temperature
Treat “heat/energy” like any other reactant
Adding heat favors reaction Removing heat favors reaction
Treat “heat/energy” like any other reactant
Adding heat favors reaction Removing heat favors reaction
N2 + 3 H2 2 NH3 + 22 kJN2 + 3 H2 2 NH3 + 22 kJ
12.6 kJ + H2 + I2 2 HI12.6 kJ + H2 + I2 2 HI
Do Now: Answer the following questionsDo Now: Answer the following questions
1. What is Le Chatelier’s Principle? 2. Label the forward and reverse reactions as
endothermic or exothermic:
CO (g) + 3 H2 CH4 (g) + H2O (g) + heat
3. In which direction will equilibrium shift if the temperature is increased?
4. In which direction will equilibrium shift if the temperature is decreased?
1. What is Le Chatelier’s Principle? 2. Label the forward and reverse reactions as
endothermic or exothermic:
CO (g) + 3 H2 CH4 (g) + H2O (g) + heat
3. In which direction will equilibrium shift if the temperature is increased?
4. In which direction will equilibrium shift if the temperature is decreased?
PressurePressure
Only for gases; count # of molecules on each side
If # is equal, pressure has no effect
pressure shifts towards fewer molecules
pressure shifts towards more molecules
Only for gases; count # of molecules on each side
If # is equal, pressure has no effect
pressure shifts towards fewer molecules
pressure shifts towards more molecules
Pressure ExamplePressure Example
4 NH (g) + 5 O2 (g) 4 NO (g) + 6 H2O (g)
= gas molecules = gas molecules
Increase pressure: shift (more to less) 9 10
Decrease pressure: shift (less to more) 9 10
4 NH (g) + 5 O2 (g) 4 NO (g) + 6 H2O (g)
= gas molecules = gas molecules
Increase pressure: shift (more to less) 9 10
Decrease pressure: shift (less to more) 9 10
N2 + 3 H2 2 NH3N2 + 3 H2 2 NH3
Equilibriumshift [N2] [H2] [NH3]
# molecules:
Increased pressure shifts towards fewer moleculesDecreased pressure shifts towards more molecules
H2 + I2 2 HIH2 + I2 2 HI
Equilibriumshift [H2] [I2] [HI]
# molecules:
Increased pressure shifts towards fewer moleculesDecreased pressure shifts towards more molecules
Conclusion QuestionsConclusion Questions
1. How does a system at equilibrium respond to a stress? List the factors that can be stresses on an equilibrium system.
1. How does a system at equilibrium respond to a stress? List the factors that can be stresses on an equilibrium system.
Conclusion QuestionsConclusion Questions
2. Given the reaction at equilibrium:
N2 (g) + 3 H2 (g) 2 NH2 (g) + heat
Which stress would cause the equilibrium to shift to the left? (a) Increasing the temperature (b) Adding N2 (g) to the system (c) Adding H2 (g) to the system
2. Given the reaction at equilibrium:
N2 (g) + 3 H2 (g) 2 NH2 (g) + heat
Which stress would cause the equilibrium to shift to the left? (a) Increasing the temperature (b) Adding N2 (g) to the system (c) Adding H2 (g) to the system
Conclusion QuestionsConclusion Questions
2. Given the reaction at equilibrium:
N2 (g) + O2 (g) 2 NO (g)
If the concentration of N2 (g) is increased, the concentration of O2 (g) will (a) Decrease (b) Remain the same (c) Increase
2. Given the reaction at equilibrium:
N2 (g) + O2 (g) 2 NO (g)
If the concentration of N2 (g) is increased, the concentration of O2 (g) will (a) Decrease (b) Remain the same (c) Increase
top related