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Reaction rates

By Carolyn Stevens and Alyce Casey. Reaction rates. Collision Theory. The collision theory is the process where the reacting particles collide, with enough energy to break the bonds and reconstruct them to form a new product.

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Reaction rates

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  1. By Carolyn Stevens and Alyce Casey Reaction rates

  2. Collision Theory • The collision theory is the process where the reacting particles collide, with enough energy to break the bonds and reconstruct them to form a new product. • Activated Complex – the partial bonding that occurs in the brief moment between bond disruption and bond formation • Activation Energy – the minimum amount of energy required in order for an effective collision to occur

  3. Activation Energy Energy of Reaction (ΔH)

  4. Factors That Affect Reaction Rates • Nature of the Reactants weak bond → increases collision efficiency → faster reaction

  5. Factors That Affect Reaction Rates • Surface Area (only affects solids) crushing → increases surface area → increases collision frequency → faster reaction

  6. Factors That Affect Reaction Rates • Concentration (only affects liquids and gases) increased pressure (gases only) → increases concentration → more particles → increases collision frequency → faster reaction

  7. Factors That Affect Reaction Rates • Temperature (endothermic and exothermic) increased temperature → higher Ek → faster particles → increases collision frequency → faster reaction

  8. Factors That Affect Reaction Rates • Catalyst (creates an alternate path for the reaction without being changed) catalyst → lower energy barrier → increases collision frequency → faster reaction

  9. Calculating Reaction Rates

  10. Example Question Prize for whoever answers correctly first! • In the decomposition reaction 2 N2O5(g) → 4 NO2(g) + O2(g) that takes place in 1.5L of pure carbon tetrachloride solution, 0.04 moles of O2 are produced over 5.7 minutes. • Calculate (a) the rate of production of O2 gas and (b) the loss of N2O5 (g).

  11. Answer to Example Question Answer to part (a): Answer to part (b): (0.047 mol/L/min)(2) = 0.0094 mol/L/min N2O5

  12. Works Cited • "Chemical bonds." JCCC Staff and Faculty Pages. Web. 15 Dec. 2009. <http://staff.jccc.net/PDECELL/chemistry/bonds.html>. • "Factors Affecting Reaction Rates." Centre for Distance Learning and Innovation. Web. 11 Dec. 2009. <http://www.cdli.ca/sampleResources/chem3202/unit01_org 01_ilo03/b_activity.html>. • "Lesson Index Chapter 10." Web. 11 Dec. 2009. <http://www.fordhamprep.org/gcurran/sho/sho/lessons/lessi ndex10.htm>. • "Measurements." Welcome to Mr Wolfe's Science. Web. 11 Dec. 2009. <http://wolfesscience.com/measurements.htm>. • "Optimize." ~ listen the world ~. Web. 16 Dec. 2009. <http://listentheworld.wordpress.com/category/optimize/>. • Therrien, Eric. Chemistry 12. Print.

  13. The End

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