Activation energy is the minimum energy required to
- A. melt the reactants
- B. break all the bonds in the products
- C. form the activated complex from the reactants
- D. keep the products stable
Explanation
Reactant molecules must climb an energy barrier to reach the transient, unstable arrangement called the activated complex or transition state, from which they can fall through to products. The height of that barrier controls the rate, while the difference in energy between reactants and products controls the enthalpy change. The two quantities are independent, which is why a very exothermic reaction can still be extremely slow.