A catalyst is a substance that speeds up a chemical reaction by lowering the activation energy—the minimum amount of energy required for the reaction to occur. By reducing this energy barrier, catalysts make it easier for reactants to convert into products, allowing the reaction to proceed faster and often under milder conditions.
Importantly, a catalyst is not consumed or permanently altered in the reaction, meaning it can be used repeatedly.
There are two main types of catalysts:
- Homogeneous catalysts: in the same phase as the reactants (e.g., acids in solution).
- Heterogeneous catalysts: in a different phase (e.g., solid metal catalysts in gas-phase reactions).
Examples:
- Enzymes act as biological catalysts in living organisms.
- Platinum catalyzes reactions in car exhaust systems.
- Iron is used as a catalyst in the Haber process for making ammonia.
Catalysts are vital in industry, biology, and environmental processes, improving efficiency and reducing energy consumption.