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Discuss the role of iron as a heterogeneous catalyst in the Haber process - AQA - A-Level Chemistry - Question 4 - 2021 - Paper 1
Question 4
Discuss the role of iron as a heterogeneous catalyst in the Haber process. Your answer should include: - the meaning of the term heterogeneous catalyst - how iron ... show full transcript
Worked Solution & Example Answer:Discuss the role of iron as a heterogeneous catalyst in the Haber process - AQA - A-Level Chemistry - Question 4 - 2021 - Paper 1
Step 1
Meaning of the term heterogeneous catalyst
Answer
A heterogeneous catalyst is a catalyst that exists in a different phase (solid, liquid, or gas) from the reactants. In the context of chemical reactions, this means that the catalyst is often in a solid form while the reactants are in the gaseous or liquid state. This phase difference allows for easier separation of the catalyst from the products after the reaction.
Step 2
How iron acts as a heterogeneous catalyst
Answer
In the Haber process, iron serves as a solid catalyst that facilitates the synthesis of ammonia from nitrogen and hydrogen gases. The process involves the adsorption of reactant molecules onto the surface of the iron catalyst, where they undergo reaction. The solid iron provides active sites for the reactants to interact, overcoming the energy barrier for the reaction and allowing for a more efficient reaction pathway.
Step 3
Factors that affect the efficiency and lifetime of the catalyst
Answer
Several factors impact the efficiency and lifetime of iron as a catalyst. These include:
- Temperature: Higher temperatures generally increase reaction rates but may also lead to catalyst degradation.
- Pressure: Increasing pressure enhances the reaction rate in the Haber process as it favors the formation of ammonia.
- Poisoning: The presence of impurities can poison the catalyst, reducing its effectiveness.
- Surface Area: A larger surface area of the iron increases the number of active sites available for the reaction, thereby enhancing its efficiency.
- Recycling and regeneration: Proper handling and regeneration processes can extend the lifespan of the catalyst by restoring its activity.