A certain elementary reaction is highly exothermic
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
A certain elementary reaction is highly exothermic, yet its energy profile still shows a positive activation energy. Which of the following best explains why the activation energy is positive?
(a) Energy must be supplied to offset the entropy decrease when ordered products form, so the activation energy remains positive.
(b) Because no catalyst has been added yet, the reaction pathway inherently has a positive activation energy; a catalyst could make it zero or negative.
(c) Breaking some bonds in the reactants first requires an input of energy, creating a barrier that is overcome before the energy-releasing steps occur.
(d) Additional energy has to be added so that the reactants and products have equal potential energy; this added energy is the activation energy.