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Published byAlfred Logan Modified over 8 years ago
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Chemical Kinetics – study of the rates of chemical reactions
Some reactions we would like to speed up Some reactions we would like to slow down
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What are 4 ways to change the rate of a chemical reaction?
Link #1 Link #2 Link #3 Link #4
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How can we change the rate of chemical reactions?
Change Concentration (or pressure of gases) Change Surface area of a solid video link Change Temperature Add a catalyst
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Increasing Concentration Increases # of Collisions
Link to Collision Theory Animation II
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For each pair of pictures which reaction will be faster and why?
Increasing surface area of solids increases reaction rate by increasing number of collsions
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Which set of conditions high pressure or low pressure will produce a faster reaction between gases and why? INCREASING PRESSURE OF GASES INCREASES THE REACTION RATE BY INCREASING THE NUMBER OF COLLISIONS
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Reactions need a minimum energy (activation energy, Ea) to occur
Link to collision theory animation
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Height of Ea determines rxn rate; smaller ea = more molecules that have enough energy to overcome ea = faster rxn
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Impact of temperature on Reaction Rate
↑ Temp → ↑ ave speed → ↑ Energy of collisions % of molecules with Energy ≥ Ea increases at higher T Link to Phet Simulation
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Catalysts accelerate reactions without being consumed by lowering the energy of activation
Lower Ea = Faster rxn Enzyme link
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Reaction requires collisions in the correct orientation
The two specific atoms in the different molecules that are reacting have to collide Link to animation
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Collision theory- atomic level explanation of reaction rates
Requirements for a chemical Reaction: Collision between reacting molecules # of collisions can be increased by : i) Increasing concentration ii) Increasing surface area for solid reactants 2) Collision must have sufficient Energy Energy of collisions impacted by: i) Temperature, ↑ Temp → ↑ ave speed → ↑ Energy of collisions ii) Catalyst – speeds up reaction without being consumed by lowering energy of activation 3) Collisions must have correct orientation
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Summary OF Collision Theory
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Link to Phet Simulation Link to Collision Theory Animation II
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Link to reaction profile diagram animation Link to collision theory animation
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Chem Demos II – Chapter 22 – Iodine Clock (concentration and temperature) Chem Demos II Chapter 20 – Catalyst Surface Area- Demo with alka seltzer tablets Chem Demos Side 2 #1 Water Gas; #2 Hydrogen Chlorine Cannon; 2nd Day Rxn Profile Diagrams N2/I2
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