MiniUnit ~ Kinetics (Chapter 17) And you

Chemical kinetics is the study of the rates of reactions, how fast or slow a reaction occurs. By understanding, on the atomic level, how a reaction occurs (its mechanism), we can learn to control the rate of a reaction. Understanding is POWER!!!!! VEBc VEBc Skip 4:15 to 8:15 – stop at 9:00

Collision Theory (Section 17.1) Collision theory provides an atomic level explanation of reaction rates. There are three basic requirements for a chemical reaction: 1) Collisions between molecules: 2) Energy of collisions: more energy, faster reaction rate and vice versa 3) Collisions must have correct orientation

1) Collisions between molecules: more collisions, faster reaction rate and vice versa Number of collisions increased by: 1. Increasing concentration (or pressure for gases) 2. Increasing surface area for solid reactants

Surface area demo here

2) Energy of collisions: more energy, faster reaction rate and vice versa Energy of collision impacted by: 1. Temperature: increase T, speed increases, energy of collisions increases 2. Catalyst ~ speeds up a reaction (without being consumed) by lowering Ea

3) Collisions must have correct orientation

Reaction Profile Diagrams (Section 17.2) Reaction profile diagrams are a convenient method of representing energy changes that occur during chemical reactions. The diagrams provide 2 important pieces of information: 1) ∆H:Endothermic + Exothermic – High H = less stable Low H = more stable 2) E a (activation energy) is associated with the rate of the reaction. The larger the E a, the slower the reaction and vice versa.

Only particles with KE > E a can react!!! Increase T = increase KE = increase # particles that can react

Y – axis is _______________. X – axis is the ______________ ______________, or the extent to which reactants have been converted to products. (It’s similar to ____________.) Reactants always start at _____ energy. 0 Reaction Energy Progress time

Transition State = ______________ energy point at the _______ of the activation barrier. At this point, old bonds are in the process of being ____________ and new bonds are in the process of being ____________. ∆H = energy of ____________ minus energy of ____________. ∆H = P – R (memorize!) E a = difference in energy between ______________ and transition state. Maximum Top Broken Created Making bonds Breaking bonds Reactants

Catalysts: accelerate reactions (without being consumed) by lowering the energy of activation

SO a catylist Is used in the reaction but not used up in the reaction Makes the reaction rate faster because... The catalyst reduces the E a that needs to be overcome.... So more molecules can react even if they do not have as much KE...

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Congratulations That is the end of the notes for IB chem. I Now memorize everything in your workbook