Which statement best applies collision theory to preventing a dangerous reaction from occurring?

• A. Adding a catalyst increases the rate of collisions, thereby preventing dangerous reactions.
• B. Raising the pressure of gaseous reactants increases collision frequency, which prevents dangerous reactions.
• C. Lowering the temperature reduces the frequency and energy of collisions, making the reaction less likely to occur.
• D. Increasing the concentration of reactants ensures that collisions happen more frequently, preventing dangerous reactions.

Answer: (C)

Verified step by step guidance

1. Understand that collision theory explains how chemical reactions occur when reactant particles collide with sufficient energy and proper orientation.
2. Recognize that to prevent a dangerous reaction, you want to reduce the likelihood of effective collisions, either by lowering the frequency of collisions or by reducing the energy of collisions below the activation energy.
3. Analyze each option: Adding a catalyst lowers activation energy and increases reaction rate, so it does not prevent reactions; raising pressure or increasing concentration increases collision frequency, which tends to increase reaction rate, not prevent it.
4. Identify that lowering the temperature reduces both the kinetic energy of particles and the frequency of collisions, making it less likely that collisions will have enough energy to overcome the activation barrier.
5. Conclude that lowering temperature is the best way to apply collision theory to prevent a dangerous reaction by decreasing both collision frequency and energy.