AQA GCSE FOUNDATION Chemistry: Catalysts and Their Role

Catalysts and Their Role in Chemical Reactions

What are Catalysts?

Catalysts are substances that speed up chemical reactions without being consumed in the process. They work by providing an alternative reaction pathway with a lower activation energy.

Activation Energy and Catalysts

• Activation energy is the minimum amount of energy needed for a reaction to occur.
• Catalysts lower the activation energy by providing an alternative pathway for the reaction. This means that more reactant molecules have enough energy to react, leading to a faster reaction rate.

How Catalysts Work

1. Adsorption: The reactants bind to the surface of the catalyst.
2. Reaction: The reactants interact with the catalyst, forming an intermediate compound.
3. Desorption: The products detach from the catalyst's surface, leaving the catalyst unchanged.

Examples of Catalysts

• Enzymes: Biological catalysts that speed up reactions in living organisms.
• Platinum: Used in catalytic converters in cars to convert harmful gases into less harmful ones.
• Nickel: Used in the hydrogenation of unsaturated fats to produce margarine.

Key Features of Catalysts

• Remain unchanged: Catalysts are not consumed in the reaction.
• Specific: Catalysts often work for specific reactions.
• Can be poisoned: Certain substances can bind to the catalyst and prevent it from working.

Importance of Catalysts

• Industry: Catalysts are essential for many industrial processes, such as the production of plastics, fertilizers, and fuels.
• Environment: Catalysts are used to reduce pollution and improve air quality.
• Biology: Enzymes are crucial for all life processes.

Key Terms

• Catalyst: A substance that speeds up a reaction without being consumed.
• Activation energy: The minimum energy required for a reaction to occur.
• Intermediate: A temporary compound formed during a reaction.
• Poison: A substance that inhibits the activity of a catalyst.

Summary

Catalysts are essential for many chemical processes. They speed up reactions by providing an alternative reaction pathway with a lower activation energy. Understanding the role of catalysts is crucial for understanding how chemical reactions work and for developing new technologies.