Collision Model - AP Chemistry

1. How does increased temperature affect the rate constant $k$?

   Increases $k$. Exponential increase due to more energetic molecules.

2. How does surface area affect the rate of reaction?

   Increases the rate of reaction. More exposed reactant particles available for collisions.

3. Find the unit for the rate constant $k$ in a second-order reaction.

   $\text{M}^{-1}\text{s}^{-1}$. Second-order reactions have rate proportional to concentration squared.

4. What is the role of proper orientation in molecular collisions?

   Ensures effective collisions. Molecules must align correctly for bonds to form.

5. What does the symbol $R$ stand for in the Arrhenius equation?

   Universal gas constant. Physical constant relating energy and temperature scales.

6. Identify the symbol for activation energy in the Arrhenius equation.

   $E_a$. Energy barrier term in exponential function.

7. Choose the factor that does not affect the frequency factor $A$ in the Arrhenius equation.

   Catalyst. Among temperature, concentration, and pressure, catalysts don't affect $A$.

8. State the effect of decreasing surface area on collision frequency.

   Decreases collision frequency. Less surface area means fewer molecules accessible for collision.

9. What is the impact of a catalyst on the frequency factor $A$?

   No impact on $A$. Catalysts only affect activation energy, not collision frequency.

10. State the impact of a catalyst on the equilibrium position.

    No impact on equilibrium position. Catalysts only affect reaction rates, not thermodynamic equilibrium.

11. What is the effect of a non-effective collision on reaction rate?

    No effect on reaction rate. Unsuccessful collisions do not produce products or affect rate.

12. Define the term 'frequency factor' in the context of the Arrhenius equation.

    Number of collisions with correct orientation. Represents collision frequency and steric factors in Arrhenius equation.

13. Calculate the effect of doubling concentration on reaction rate in a first-order reaction.

    Rate doubles. Rate is directly proportional to concentration in first-order kinetics.

14. Choose the correct unit for the rate constant $k$ in a first-order reaction.

    $\text{s}^{-1}$. First-order rate depends linearly on one concentration.

15. What does the Arrhenius equation describe?

    Relationship between rate constant and temperature. Shows how rate constant depends exponentially on temperature.

16. Identify the effect of catalysts on activation energy.

    Catalysts lower activation energy. Provides alternative pathway with lower energy barrier.

17. What is the effect of increasing activation energy on the rate constant $k$?

    Decreases $k$. Higher barrier reduces fraction of molecules with sufficient energy.

18. What is the relationship between reaction rate and activation energy?

    Inverse relationship. Higher $E_a$ means fewer molecules have sufficient energy to react.

19. State the unit of the rate constant $k$ in a zero-order reaction.

    $\text{M} \text{s}^{-1}$. Zero-order rate is independent of concentration.

20. Identify how pressure affects the reaction rate for gaseous reactants.

    Increases reaction rate. Compression brings gas molecules closer increasing collision frequency.

21. What is the effect of a higher activation energy on the reaction rate?

    Decreases reaction rate. Fewer molecules have energy to overcome higher barrier.

22. Identify how temperature affects the activation energy $E_a$.

    Temperature does not affect $E_a$. Activation energy is an intrinsic property independent of temperature.

23. Define effective collision.

    Collision with sufficient energy and proper orientation. Both energy and orientation requirements must be met.

24. What is the effect of decreasing activation energy on effective collisions?

    Increases effective collisions. More molecules now have sufficient energy to overcome barrier.

25. What is the basic principle of the collision model?

    Molecules must collide to react. Fundamental assumption that reactions require molecular contact.

26. What term describes the minimum energy required for a reaction to occur?

    Activation energy. Energy barrier that must be overcome for bonds to break and form.

27. What impact does temperature have on kinetic energy of molecules?

    Increases kinetic energy. Higher temperature increases average molecular speeds.

28. State the effect of temperature on collision frequency.

    Increases collision frequency. Higher temperature means faster molecular motion and more collisions per unit time.

29. What is the primary role of a catalyst in a chemical reaction?

    Lowers activation energy. Speeds up reactions by providing alternative reaction pathway.

30. What does the symbol $k$ represent in the Arrhenius equation?

    Rate constant. Proportionality constant relating concentration to reaction rate.

31. What factor besides temperature can increase the rate constant $k$?

    Catalyst. Only catalysts and temperature significantly affect $k$.

32. Write the Arrhenius equation.

    $k = A e^{-Ea/RT}$. Mathematical expression showing temperature dependence of rate constant.

33. Identify one condition necessary for a collision to be effective.

    Sufficient energy. Energy threshold that molecules must exceed during collision.

34. What is the relationship between reaction rate and temperature?

    Direct relationship. Higher temperature exponentially increases rate constant.

35. State the effect of a catalyst on the overall reaction rate.

    Increases reaction rate. Lowers activation energy allowing more effective collisions.

36. What does $A$ represent in the Arrhenius equation?

    Frequency factor. Pre-exponential term representing collision frequency.

37. How does increasing concentration affect reaction rate?

    Increases reaction rate. More molecules present means higher collision frequency.

38. Find the effect of increasing the pressure on the reaction rate of gases.

    Increases reaction rate. Higher pressure brings gas molecules closer together.

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