What is the term for the minimum energy required for a reaction to occur?
A) Activation energy
B) Equilibrium constant
C) Free energy
D) Transition state
The correct answer and explanation is:
The correct answer is A) Activation energy.
Explanation:
Activation energy refers to the minimum energy required for a chemical reaction to take place. It is the energy needed to break the bonds in the reactants so that new bonds can be formed in the products. This energy barrier must be overcome for a reaction to proceed, regardless of the reaction’s direction. The activation energy is a critical factor in determining the rate at which a reaction occurs.
For most chemical reactions, the reactants must absorb energy to reach the transition state, a temporary, unstable arrangement of atoms where bonds are breaking and forming. The activation energy is the difference between the energy of the reactants and the highest energy level reached during the reaction (the transition state). Once the activation energy is provided, the reactants are able to move through the transition state and proceed to form products.
The rate of reaction is influenced by the activation energy. The lower the activation energy, the faster the reaction occurs, because a larger proportion of reactant molecules will have enough energy to overcome the barrier at any given temperature. Conversely, reactions with high activation energies proceed more slowly unless the temperature is increased or a catalyst is used.
While activation energy is the energy needed to initiate a reaction, other terms like equilibrium constant (B), free energy (C), and transition state (D) relate to different aspects of chemical reactions. The equilibrium constant describes the ratio of concentrations of products to reactants at equilibrium, free energy is the energy available to do work, and the transition state refers to the intermediate structure formed during a reaction, not the energy required to overcome the barrier. Therefore, activation energy is the correct term for the minimum energy needed for a reaction to occur.