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Effect of catalysts on rate of reaction

Answer Text:
Effect of catalysts on rate of reaction:
- Catalysts are substances which alter the rate of a chemical reaction without being consumed, e.g. finely divided iron in the harber process;
- They alter the rate of a chemical reaction but remain unchanged at the end of the reaction;
- They can therefore be reused at the end of the reaction;
Modes of action of catalysts:
-Provision of a surface over which particles can react.
Note: Due to this solid catalysts are more effective when used in powder form;
-Formation of short-lived intermediate compounds with products which then break up to give the products and the catalyst;
-By adsorption;
Note: - Generally, a catalyst increases the rate of a reaction by providing a different pathway of lower activation energy.
- This means more collisions can overcome this energy barrier and result in a reaction.
- It lowers the activation energy of the reaction;
- Catalysts are also reaction specific;