Collision Theory Reaction Rates

1. Collision Theory Reaction Rates

2. Collision Theory I No Reaction H I H 1) Atoms, ions, and molecules must collide in order to react.

3. Collision Theory I No Reaction H I H 2) Reacting substances must collide with the correct orientation.

4. Collision Theory I No Reaction H I H 3) Reacting substances must collide with enough energy to form the activated complex.

5. Collision Theory I H I I I H H H 3) Reacting substances must collide with enough energy to form the activated complex.

6. Collision Theory 2) Reacting substances must collide with the correct orientation. 3) Reacting substances must collide with enough energy to form the activated complex. 1) Atoms, ions, and molecules must collide in order to react.

7. Activated Complex A temporary, unstable arrangement of atoms that may form products or reactants.

8. Activation Energy (Ea) Minimum amount of energy needed in a collision to form the activated complex.

9. Expressing Reaction Rates Some chemical reactions are very fast and others are very slow. To express the rate in clearer terms:

10. Calculating Reaction Rates Use the table to determine the formation rate of NO(g): CO(g) + NO2(g) →CO2(g) + NO(g) [NO] @ t2– [NO] @ t1 rate = 0.005 mol/L⦁s t2 – t1

11. Reaction Rates Example Using the data table, calculate the average reaction rate over the time period expressed as moles of C4H9Cl consumed per liter per second.

12. Comparing Reaction Rates Using stoichiometry, we can compare the rates of two species in a reaction. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) If C3H8 is decreasing at a rate of 2.00 M/s, at what rate is CO2 being produced?

13. Discussion Questions 1) What criteria must be met for reactant collisions to result in a successful product? The reactants must collide with each other The reactants must collide with enough energy and be in the right positions The reactants must have enough energy to form the activated complex

14. Discussion Questions 2) The most common way of expressing a reaction rate is in terms of: mol/L g/L⦁s mol/L⦁s mol/s

15. Discussion Questions 3) What is the average rate of formation of salt in the first 10 seconds of this reaction? HCl + NaOH → H2O + NaCl 0.00 M NaCl at 0.00 s 2.87 M NaCl at 10.00 s

16. Discussion Questions 4) What is the average rate of formation of CO2 between 3.00 and 7.00 seconds of this reaction? H2CO3→ H2O + CO2 1.08 M CO2 at 3.00 s 3.42 M CO2 at 7.00 s

17. Discussion Questions 5) Use the table to determine the average rate of sulfuric acid being consumed in this reaction between 4 and 8 seconds. 2Fe + 3H2SO4→ 3H2 + Fe2(SO4)3

18. Discussion Questions 6) As a reaction proceeds, the concentration of reactants will _______ and the concentration of products will ________. increase, decrease increase, increase decrease, decrease decrease, increase

19. Discussion Questions 7) Calculate the rate of formation of iron(II) sulfide if sulfur is being consumed at a rate of 0.440 mol/L⦁s. 8 Fe(s) + S8(s) → 8 FeS(s)

20. Discussion Questions 8) Calculate the rate of formation of aluminum oxide if oxygen is being consumed at a rate of 0.060 mol/L⦁s. 3 O2(g) + 4Al(s) → 2 Al2O3(s)

21. Discussion Questions 9) At what rate is aluminum being consumed if aluminum oxide is being formed at 2.50 mol/L⦁s. 3 O2(g) + 4Al(s) → 2 Al2O3(s)

22. Discussion Questions 10) At what rate is nitrogen being consumed if hydrogen is being consumed at 0.0093 mol/L⦁s. 3 H2(g) + N2(g) → 2 NH3(g)