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Factors affecting rxn rates #3

Factors affecting rxn rates #3. http://www.youtube.com/watch?v=5tFy9bOLsxw Iron Combustion!. Increasing the Rate of Reactions. 1. Increasing temperature. 2. Increasing reactant concentration.

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Factors affecting rxn rates #3

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  1. Factors affecting rxn rates #3

  2. http://www.youtube.com/watch?v=5tFy9bOLsxw Iron Combustion!

  3. Increasing the Rate of Reactions 1. Increasing temperature 2. Increasing reactant concentration 3. Adding a catalyst(aninhibitor decreases) triggers a reaction rate to increase; participates in the reactions but comes out the same way it went in. 4. Nature of the reactant(changing a reactant for a more reactive one) • Increasing the pressure • Increasing the surface area – only for heterogeneous rxns!

  4. Homogeneous Vs Heterogeneous Reactions A homogeneous reaction is one where all the reactants are in the samephase. They are fast due to thorough mixing and manycollisions! H2(g) + O2(g) → AgNO3(aq) + NaCl(aq) → same- only look at reactants!

  5. Factors that Affect the Reaction Rate Heterogeneousreactants are in two or more different phases Slow due to poor mixing and fewer collisions Zn(s) + 2HCl(aq) → Fe(s) + O2(g) →

  6. heterogeneous Classify as Homogeneous or Heterogeneous: 2.                   Ag+(aq)  +  Cl (aq)          →       AgCl  (s)                    homogeneous 1.  Zn (s)  +  2HCl (aq)       →       H2(g)  +  ZnCl2  (aq) homogeneous 3.                   H2(g)    +  F2(g)        →              2HF (g)                                     

  7. What reactions are faster? ( in general ) 1. Homo’s are fasterthan hetero’s. 2. FastestSlowest (aq) (g and l) (s) only reactants 3. Simple ionicare fastest -no bonds to break- double replacement AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) Becomes: Ag+ + NO3- + Na+ + Cl- → AgCl(s) + Na+ + NO3- Fast Ag+ + Cl- → AgCl(s) Fast simple ionic!

  8. Describe each Pair of reactions as faster or slower. 2NaClO3(aq) + F2(aq) → 2NaF(aq) + 3O2(g) + Cl2(g) Faster Homo 3H2(g) + N2(g)  2NH3(g) Homos are fast- more collisions Aqueous reactions are fasters than gaseous. Homo

  9. Describe each Pair of reactions as faster or slower. Zn(s) + 2HCl(aq)  H2(g) + ZnCl2(aq)  Faster because aq ions: 1. close proximity in soln 2. ability to move through solvent 3. strong +/- interactions. Hetero C(s) + O2(g)  CO2(g) Hetero

  10. State five ways to increase the rate of this reaction. Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq) 1. Increase temperature 2. Increase [HCl], add more Mg 3. Add a catalyst 4. Increase surface area (powder Mg) 5. Agitate

  11. Hebden, p 7. Exercises 10 – 11; p 8. Exercises 12 – 14; p 9. Exercises 15 – 16 AND 17. (Read page12 on Collision Theory to fill in the blanks for tomorrow’s lecture)

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