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Kinetics. Collision Theory: How reactions takes place. Why are kinetics important?. In order to control processes. speed up useful reactions that occur to slowly slow down reactions that are harmful Example:
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Kinetics Collision Theory: How reactions takes place
Why are kinetics important? • In order to control processes. • speed up useful reactions that occur to slowly • slow down reactions that are harmful • Example: • Catalysts are used in our cars to rapidly convert toxic substances into safer substances • Refrigerators are used to slow the process of spoiling in food
Collision Theory • How do reactions occur at the molecular level? • Molecules collide with each other • Form activated complex • Svante Arrhenius • Did some fancy math to figure out that number of collisions alone don’t account for reaction rates • He found that reactants also require: • Activation energy (Ea - energy to break bonds) Animation • Right orientation (Animation)
What affects reaction rate? • Temperature (Animation) • Increased number of collisions • More molecules have enough activation energy • Remember Maxwell-Boltzmann distribution • Increased temperature, distribution flattens out • More molecules have Ea
What affects reaction rate? • Higher concentration • Number of collisions increased • Animation • Animation 2 • Increased surface area • Number of collisions increased • Animation
What affects reaction rate? • Catalysts • Def’n: substance that speeds up a rxn w/o being used up itself • Number of collisions with Ea increase • Ea lowers • Catalysts hold molecules in right orientation • Homogeneous catalyst (same phase of matter) • Demo: Catalysis by Co2+ (demo) • Heterogeneous catalyst (different phase) Animation