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!!!!! https://www.youtube.com/watch?v=7qOFtL3VEBc 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) Ea (activation energy) is associated with the rate of the reaction. The larger the Ea, the slower the reaction and vice versa.

Only particles with KE > Ea 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. Energy Reaction 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!) Ea = 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 Ea 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