1. The student will learn:
1. Using LeChatelier’s principles be able to
predict production of the reaction based on the stress placed upon a reaction

2. Two opposing changes occur at ‘equal rates’
Reversible reaction
A chemical reaction in which the products can react to form the reactants.
Examples in your life : baby make-up, match box cars, pencils, shirts, prescription sunglasses.
Equilibrium:
Two opposing changes occur at ‘equal rates’
Q: When is a reaction that is reversible considered to have reached equilibrium?
A: When forward reaction rate = reverse reaction rate.
Caution:: Equilibrium….equal… it may appear all has stopped but not so……. Very dynamic, frantic activity, not static.

3. Closed system: Matter can not enter or exit.
Reaction Equilibrium
Closed system: Matter can not enter or exit.
“ but energy can” example: sunlight, heat from a burner, cooling by ice
Le Chatelier’s Principle: if a system at equilibrium is subjected to a stress then the reaction will be shifted in the direction to relieve the stress.
We will learn 4 stress effects :
change in pressure
change in temperature
change in concentration
adding a catalysts

4. 3H2 (g) + N2 (g) 2NH3 (g) + heat C (s) + H2 (g) + heat CO (g) + H2 (g)
Change the pressure:
an increase in pressure will favor a shift toward
the side with lowest number of gas particles.
3H2 (g) + N2 (g) 2NH3 (g) + heat
C (s) + H2 (g) + heat CO (g) + H2 (g)

5. Change the temperature:
increasing Temperature will drive the reaction toward the reactants (shift to left) if exothermic.
increasing temperature will drive the reaction toward the products (shift to right) if endothermic.
3C + Fe2O3 3CO + 2Fe kj
2H2O kj H2(g) + O2(g)

6. “see-saw ride principle”
Change in Concentration:
adding more reactants always drives the reaction toward the products (shift to the right)
adding more products always drives the reaction toward the reactants ( shift to the left)
“see-saw ride principle”
3 H2 + N2 2NH3
CaCO3 CaO + CO2
Ca(OH)2 CaO + H20
Fe2O3 + 3CO Fe + 3CO2

7. Adding a Catalyst:
does not cause a shift in equilibrium
speed up or slow down only
How do they show a catalyst?

8. H2(g) Cl2(g) 2HCl(g) kj
Predict: forward, reverse, neither……
Addition of chlorine
Remove HCl
Increase pressure
Decrease temperature
Remove hydrogen
Decrease pressure
Add a catalyst
Increase temperature
Decrease system volume

9. PCl3(g) + Cl2(g) + 92.5kj PCl5(g)
Predict: forward, reverse, neither…..
Increase in temperature
Decrease in pressure
Decrease in volume
Add more chlorine gas
Add a catalyst
Add phosphorus pentachloride
Increase the pressure
Decrease the temperature
Add more phosphorus trichloride

10. The student will learn:
1. Using LeChatelier’s principles be able to
predict production of the reaction based on the stress placed upon a reaction