What is activation energy, and how does it work? Select one: The difference between reactants and products in terms of free energy The amount of energy needed to start a chemical reaction The energy released when chemical bonds are broken The thermal energy released by random molecular motions.
The Correct Answer and Explanation is:1
The correct answer is: The amount of energy needed to start a chemical reaction.
Explanation:
Activation energy refers to the minimum energy required to initiate a chemical reaction. It is the energy that must be supplied to the reactant molecules for the reaction to occur. This energy is necessary to overcome the energy barrier that exists for the reaction to proceed.
When chemical reactions occur, bonds in the reactant molecules must be broken before new bonds can form to produce products. The activation energy is the energy required to break these bonds and form an activated complex or transition state. This complex is a high-energy, unstable intermediate that exists momentarily before the reaction proceeds to form the products.
Activation energy is essential because, in most reactions, molecules must collide with sufficient energy and in the correct orientation to react. The amount of energy needed to break bonds in the reactant molecules is typically higher than the energy released when new bonds are formed in the products. Therefore, even if a reaction is energetically favorable (i.e., the products are lower in energy than the reactants), activation energy still needs to be supplied for the reaction to proceed.
For example, in combustion reactions, the reactants (such as fuel and oxygen) are in a stable state, and energy (in the form of heat or a spark) is required to break the bonds in the reactants to start the reaction. Once the reaction starts, the energy released by forming new bonds in the products (like carbon dioxide and water) is sufficient to sustain the reaction.
The lower the activation energy, the faster the reaction tends to occur, and catalysts can help lower this energy barrier, making reactions proceed more quickly without being consumed in the process.
