The correct answer is option 3. Decreasing activation energy of reaction.
A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. The activation energy is the minimum energy required for reactant molecules to undergo the chemical transformation and form products. By lowering the activation energy, a catalyst facilitates the reaction to occur more readily, allowing it to proceed at a faster rate.
Here is a detailed explanation:
1. Activation Energy (Ea): In a chemical reaction, reactant molecules need to overcome a certain energy barrier known as the activation energy (Ea) to transform into products. The activation energy represents the energy required to break bonds in the reactant molecules and initiate the chemical reaction.
2. Catalysis: A catalyst is a substance that participates in a chemical reaction and increases the rate of the reaction by providing an alternative reaction pathway with a lower activation energy. Importantly, a catalyst is not consumed in the reaction, meaning it remains unchanged chemically and is available to facilitate multiple reaction cycles.
3. Lowering Activation Energy: The catalyst achieves an increase in reaction rate by lowering the activation energy required for the reaction. It does so by providing an alternative mechanism or pathway for the reaction to proceed. This alternative pathway typically involves the formation of an intermediate species with a lower activation energy compared to the original pathway.
4. Reaction Mechanism: The catalyst interacts with the reactant molecules, forming an intermediate complex. This complex may involve temporary bonds between the catalyst and reactants, stabilizing certain transition states and making it easier for the reaction to occur.
5. Overall Effect: By providing a lower energy pathway, the catalyst allows a more significant fraction of reactant molecules to overcome the activation energy barrier and transform into products. As a result, the reaction rate increases.
So, to answer the question, a catalyst increases the rate of reaction by decreasing the activation energy of the reaction. This is crucial in making the reaction proceed more efficiently and quickly, but it does not alter the thermodynamics or the overall energy change associated with the reaction. |
