Factors affecting reaction rate Knowledge-Based Practice

Questions

1. 1.

   Why do aqueous ionic reactions, such as precipitation, typically occur much faster than reactions between covalent molecules under identical experimental conditions?

   • A) Aqueous ions possess a significantly higher average kinetic energy than neutral covalent molecules at the same temperature.
   • B) Ionic precipitation reactions are always exothermic, which inherently guarantees a much higher reaction rate.
   • C) Water molecules act as homogeneous catalysts that selectively accelerate reactions between charged particles.
   • D) Ionic reactions involve electrostatic attraction between pre-existing ions with virtually zero activation energy, whereas covalent reactions require energy to break existing bonds.
2. 2.

   According to collision theory, which of the following best explains why an increase in the concentration of a dissolved reactant leads to an increased reaction rate?

   • A) It lowers the activation energy required for the reaction to occur.
   • B) It increases the average kinetic energy of the reacting solute particles.
   • C) It increases the fraction of molecular collisions that possess energy equal to or greater than the activation energy.
   • D) It increases the number of reacting particles per unit volume, thereby increasing the frequency of collisions.
3. 3.

   How does increasing the surface area of a solid reactant increase the rate of a heterogeneous chemical reaction?

   • A) It increases the number of exposed reactant particles, leading to a higher frequency of collisions per unit time.
   • B) It lowers the activation energy required for the reaction to proceed.
   • C) It increases the average kinetic energy of the reacting solid particles.
   • D) It provides an alternative reaction pathway with a more stable intermediate.
4. 4.

   Which of the following statements correctly describes how a catalyst increases the rate of a chemical reaction?

   • A) It provides an alternative reaction pathway with a lower activation energy.
   • B) It increases the average kinetic energy of the colliding reactant particles.
   • C) It increases the enthalpy change between the reactants and the products.
   • D) It increases the total frequency of collisions by raising reactant concentration.
5. 5.

   Which of the following statements correctly explains why an increase in temperature increases the rate of a chemical reaction according to collision theory?

   • A) It increases the average kinetic energy of the particles, thereby increasing the fraction of collisions that have energy greater than or equal to the activation energy.
   • B) It lowers the activation energy of the reaction pathway, allowing collisions with less energy to form products.
   • C) It increases the total collision frequency while keeping the proportion of effective collisions unchanged.
   • D) It increases the potential energy of the activated complex, making the transition state more stable.

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