Chem CH 17

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This deck includes 12 flashcards covering activation energy, reaction mechanism, endothermic reaction, and related concepts. Use it to review key Chemistry ideas, focus on weak cards, and prepare for your exam with StudyLess.

1. 01

   What is an Activated Complex?

   A transitional structure that results from an effective collision and that persists while old bonds break and new bonds form.

2. 02

   What does ΔE represent in a reaction pathway?

   The overall energy change of reaction, which is the difference between reactants and products.

3. 03

   What is the activation energy for an exothermic reaction?

   The difference between the reactants and the activated complex.

4. 04

   What is a Reaction Mechanism?

   Step-by-step sequence of reactions by which the overall chemical change occurs.

5. 05

   What type of reaction is a reverse reaction?

   Endothermic reaction.

6. 06

   What is the activation energy for an endothermic reaction?

   The difference between the products and the activated complex.

7. 07

   Why is an endothermic reaction considered less favorable?

   Because the activation energy needed is much bigger.

8. 08

   What is Activation Energy?

   Minimum energy required to transform the reactants into activated complex.

9. 09

   What are Intermediates in a reaction mechanism?

   Species shown in the reaction mechanism but not shown in the overall equation.

10. 10

    What two conditions must a collision meet to produce products according to the Collision Theory?

    Collision must be energetic enough and in correct orientation (angle).

11. 11

    What is the impact of Activation Energy on enthalpy?

    Has no impact on the enthalpy but is needed to provide enough energy to start the reaction.

12. 12

    What are Homogeneous reactions?

    Reactions where all reactants and products are in the same physical state.

13. 13

    How does temperature affect reaction rate?

    Increased temperature increases kinetic energy, leading to more effective collisions.

14. 14

    How does the concentration of reactants affect reaction rate?

    More molecules lead to more collisions.

15. 15

    What is a catalyst?

    Substance that changes the reaction rate without being consumed.

16. 16

    What does a catalyst do?

    Lowers the activation energy and usually speeds up the reaction; ΔE doesn't change.

17. 17

    What is a homogeneous catalyst?

    It is in the same phase as reactants and products.

18. 18

    What is a heterogeneous catalyst?

    It is in a different phase as reactants.

19. 19

    What is the rate law?

    Equation that relates the rate of reaction and concentration of reactants at constant temperature.

20. 20

    In the rate law R = k[A]ⁿ[B]ᵐ, what do R, k, [A], [B], n, and m represent?

    R is reaction rate, k is constant, [A]/[B] are reactant concentrations, n/m are orders.

21. 21

    What is the overall order of a reaction?

    The sum of the individual orders (n+m).

22. 22

    What happens to the reaction rate if the concentration of a reactant in a second-order reaction doubles?

    The reaction rate quadruples.

23. 23

    What characterizes a zero-order reaction with respect to a reactant?

    The concentration of that reactant doesn't affect the reaction rate.

24. 24

    What is the specific rate constant (k)?

    The proportionality constant relating the rate of reaction to reactant concentrations.

25. 25

    How is the value of k determined?

    It must be determined from experimental data once reaction orders are known.

26. 26

    Is the value of k the same for all reactions?

    No, k is for a specific reaction and has a different value for other reactions.

27. 27

    What determines the units of k?

    The units of k depend on the overall order of the reaction.

28. 28

    How do different concentrations of reactants or products affect the value of k?

    The value of k does not change for different concentrations of reactants or products.

29. 29

    How does temperature affect the value of k?

    If temperature increases, the value of k increases.

30. 30

    How does the presence of a catalyst affect the value of k?

    The value of k changes (becomes larger) if a catalyst is present.

31. 31

    What is reaction rate?

    Change in concentration of reactants per unit time.

32. 32

    What are the factors that affect the reaction rate?

    Nature of reactants, surface area, temperature, concentration, presence of catalyst.

33. 33

    How does surface area affect reaction rate?

    Physically increasing surface area leads to an increase in effective collisions.

34. 34

    What is a heterogeneous reaction?

    Reactants are in different phases.