Question

According to collision theory, increasing the starting concentration of a collection of reacting molecules directly results in a change in which of the following system factors?

• A. Activation energy
• B. Collision frequency
• C. Rate constant
• D. Fraction of molecules with energy greater than activation energy

Hint:

Concentration adjustments physically manipulate the collision frequency (\(Z\)). Changing the temperature adjusts both the rate constant (\(k\)) and the fraction of high-energy molecules.

Answer 1

The Correct Option is B

Concept: Collision theory models reaction rates based on effective interactions between molecules per unit volume per second, mathematically formulated as: \[ \text{Rate} = Z_{AB} \cdot e^{-\frac{E_a}{RT}} \] Where \(Z_{AB}\) is the collision frequency factor.

Step 1: Analyzing the effect of crowded molecular environments.
Increasing reactant concentration places more molecules inside the same spatial boundaries. This physical crowding directly maximizes structural encounters, leading to a major increase in the collision frequency (\(Z_{AB}\)). Factors like activation energy (\(E_a\)) and the energetic fraction depend exclusively on temperature and catalysts.