At 300 K, experiments show that about 4 % of collisions between H₂ and Cl₂ molecules…
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
At 300 K, experiments show that about 4 % of collisions between H₂ and Cl₂ molecules possess at least the minimum energy required for their elementary reaction. When the temperature is raised to 310 K, that fraction increases to roughly 7 %, while the total collision frequency changes negligibly.
Which of the following best explains why the initial reaction rate at 310 K is approximately twice that at 300 K?
(a) The activation energy of the reaction decreases as temperature increases, making collisions more effective.
(b) Higher temperature increases the molar concentration of the reactants, leading to more frequent collisions.
(c) A greater proportion of collisions now have sufficient kinetic energy to overcome the activation barrier.
(d) The higher thermal energy allows reactant molecules to collide with a larger cross-section, so the collision frequency essentially doubles.