Unit 7 Notes Part 1
Chemical Kinetics The area of chemistry concerned with the speed at which reactions occur is called chemical kinetics. – Reaction rate is the change in concentration of reactants and products in a certain amount of time. Average rate of reaction = Δ [reactant or product] Δ time
Collision Theory Key Idea: Molecules must collide to react. In order to react molecules and atoms must come in contact with each other. They must hit each other hard enough to react. Anything that increase these will make the reaction occur faster.
Energy Reaction coordinate Reactants Products
Energy Reaction coordinate Reactants Products Activation Energy - Minimum energy to make the reaction happen
Energy Reaction coordinate Reactants Products Overall energy change
Endothermic Reactions
Exothermic Reactions
Your To-Do List for Today Work independently and quietly! In your books: Read & take notes on “Reaction Rates” on pg Answer Question #1 on pg 731 Read & take notes on 22-2 on pg Answer Questions #1,2,5 on pg. 737 Read & take notes on 22-3 on pg Answer Questions #1-3 DUE MONDAY!!
2NO 2 (g) 2NO(g) + O 2 (g) Reaction Rates: 2. Can measure appearance of products 1. Can measure disappearance of reactants 3. Are proportional stoichiometrically
DMA#8 4/15/13 Name 3 things that could increase the rate at which a chemical reaction happens. 4 th Period- Get out homework for grading!
Catalyst: A substance that speeds up a reaction without being consumed Enzyme: A large molecule (usually a protein) that catalyzes biological reactions.
Catalysis Catalyst: A substance that speeds up a reaction without being consumed Enzyme: A large molecule (usually a protein) that catalyzes biological reactions. Homogeneous catalyst: Present in the same phase as the reacting molecules. Heterogeneous catalyst: Present in a different phase than the reacting molecules.
Pt surface HHHH HHHH Hydrogen bonds to surface of metal. Break H-H bonds Catalysts
Pt surface HHHH Catalysts C HH C HH
Pt surface HHHH Catalysts C HH C HH The double bond breaks and bonds to the catalyst.
Pt surface HHHH Catalysts C HH C HH The hydrogen atoms bond with the carbon
Pt surface H Catalysts C HH C HH HHH
Catalysts increase the number of effective collisions.
Exothermic Reaction with a Catalyst This is the same graph you sketched last time, so you can just add the new catalyst activation energy.
Endothermic Reaction with Catalyst
Energy Diagrams 1.Draw and label an energy diagram. Calculate the activation energy and change in energy of the reaction Reactants = 78.9 kJ Products = kJ Activated complex = 300 kJ Reactants = 25.1 kJ Products = 35.2 kJ Activated complex = 49.0 kJ