Presentation on theme: "16-3: Le Chatelier’s Principle. Le Chatelier’s Principle If a change is made to a system at equilibrium, the rxn will shift in the direction that will."— Presentation transcript:
Le Chatelier’s Principle If a change is made to a system at equilibrium, the rxn will shift in the direction that will allow it re-establish equilibrium
Concentration Adding more of something increases the concentration and will cause the rxn to shift to the other side Taking something out causes a decrease in conc. and the rxn will shift to that side
Why is it useful? Le Chatelier’s Principle can be used to maximize the amount of product that a reaction produces.
How would you use a change in concentration to maximize the products? 2H 2 (g) + O 2 (g) 2H 2 O(g) If, at equilibrium, there are more reactants than products, take away water as it is produced
Pressure For gaseous equilibrium systems If pressure is increased, the rxn will shift in the direction that produces fewer gaseous moles
2H 2 (g) + O 2 (g) 2H 2 O(g) 3 moles of gaseous reactants, 2 moles of gaseous products Increase the pressure. This will push it to the side with fewer gaseous mols.
Temperature Value of the equilibrium constant depends upon the temperature
Temperature Is the rxn exothermic or endothermic? Exothermic – gives off heat. If given heat, absorbs it in the reverse rxn. Endothermic – requires heat. If heat is taken away, it gets more from the reverse reaction. Think of heat as a reactant or product.
Temperature Exothermic: A + B C + heat To increase rate, cool it. Endothermic: A + heat B + C To increase rate, heat it.
Temperature Reaction rate is important, though. If you cool a rxn too much, the particles do not collide and little to no reaction will occur.
Haber Process Developed by German chemist, Fritz Haber, during WWI to help Germany produce ammonia for use in explosives
Haber Process N 2 (g) + 3H 2 (g) 2NH 3 (g) + heat Removed ammonia as it was produced Increased pressure 4 mols gaseous reactants, 2 moles gaseous products.
Haber Process 1914: Haber made head of chemical warfare service, works on gases for chemical warfare 1918: Haber wins the Nobel Prize in Chemistry 1933: Haber (who is Jewish) leaves Germany, as Hitler gains more power
Haber Process Today, the Haber process is still used to make ammonia for fertilizers and cleaning products