Question

1. Summarize the reason why some thermodynamically spontaneous reactions do not occur at a fast rate.

Answer 1

Spontaneous reactions signifies that the products will be lower in free energy than the reactants (ΔG is negative). When two reactants collide, they form a transition structure which is extremely unstable. When the transition state energy is not high enough to form the product, they will again form the reactants. Only when the transition structure has sufficiently high energy, they will form the products. It depends on the energy of colliding reactants. The higher the activation energy, the slower is the reaction.