Collision theory Knowledge-Based Practice

Questions

1. 1.

   According to collision theory, what occurs at the molecular level when two reactant particles collide with the correct spatial orientation but possess kinetic energy less than the activation energy ($E_a$)?

   • A) They form products at a reduced rate by gradually absorbing thermal energy during the impact.
   • B) They break their original chemical bonds but cannot rearrange into product molecules.
   • C) They fuse into a permanent activated complex that cannot decompose into products.
   • D) They repel each other and bounce apart elastically without breaking bonds or forming products.
2. 2.

   According to collision theory, why do gas-phase reactions between complex, asymmetrical molecules generally have a much smaller fraction of effective collisions than reactions between simple monatomic species with comparable activation energies?

   • A) Complex molecules experience lower average collision velocities at a given temperature due to greater molar masses.
   • B) Complex molecules absorb all collision energy into nonreactive vibrational modes, preventing bond cleavage.
   • C) Collisions involving polyatomic reactants violate conservation of momentum and reduce available thermal energy.
   • D) Complex molecules must collide with a specific mutual spatial orientation for the reactive functional groups to interact.
3. 3.

   According to collision theory, which of the following best explains why an increase in reactant concentration increases the rate of a chemical reaction at constant temperature?

   • A) The activation energy of the reaction is significantly decreased.
   • B) The average kinetic energy of the reacting particles increases.
   • C) The fraction of total collisions that possess sufficient energy to react increases.
   • D) The frequency of collisions between reactant particles per unit volume increases.
4. 4.

   According to collision theory, which statement best explains why an increase in temperature leads to a substantial increase in the rate of a chemical reaction?

   • A) It decreases the activation energy of the reaction pathway.
   • B) It significantly increases the fraction of collisions possessing kinetic energy equal to or greater than the activation energy.
   • C) It ensures that every collision occurs with the correct spatial orientation.
   • D) It increases the total collision frequency by several orders of magnitude.
5. 5.

   According to collision theory, which of the following conditions must be met for a collision between reactant particles to result in a successful chemical reaction?

   • A) Particles must collide with kinetic energy less than the activation energy while maintaining a favorable molecular orientation.
   • B) Particles must collide at high frequency regardless of their individual kinetic energies and spatial orientations.
   • C) Particles must collide with a favorable molecular orientation regardless of whether activation energy is achieved.
   • D) Particles must collide with kinetic energy equal to or greater than the activation energy and in a favorable molecular orientation.

Answers and step-by-step solutions appear after you finish the test.