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Catalysts for AQA GCSE Chemistry

Catalysts

This page covers the following topics:

1. Catalysts
2. Applications of catalysts

A catalyst is a substance that lowers the activation energy of a reaction by providing an alternative pathway for reaction. The catalyst doesn't take part in the reaction so will not be altered or used up.

Catalysts

Catalysts are important to many industrial and biological reactions (inside plants or animals). Biological catalysts are given the name 'enzyme' and different enzymes are present in every cell of the human body to perform a number of vital reactions.

Applications of catalysts

1

Look at this graph showing enzyme activity at different temperatures. Why does the rate of reaction fall at higher temperatures and not continue to increase?

At high temperatures the enzymes are deactivated as the structure of the proteins within them is altered (the proteins have been denatured).

Look at this graph showing enzyme activity at different temperatures. Why does the rate of reaction fall at higher temperatures and not continue to increase?

2

What is the catalyst used in the Haber process? (the reaction between nitrogen and hydrogen to form ammonia)

Iron

What is the catalyst used in the Haber process? (the reaction between nitrogen and hydrogen to form ammonia)

3

How do catalysts affect rate of reaction using collision theory?

Catalysts increase rate of reaction as they lower Ea so more particles will have sufficient energy to react and there will be more frequent successful collisions.

How do catalysts affect rate of reaction using collision theory?

4

Manganese oxide acts as a catalyst for the decomposition of hydrogen peroxide, what would be the effect of adding manganese oxide on the volume of oxygen produced in the first 10 seconds of this reaction?

More oxygen will be produced in 10 seconds if manganese oxide is present.

Manganese oxide acts as a catalyst for the decomposition of hydrogen peroxide, what would be the effect of adding manganese oxide on the volume of oxygen produced in the first 10 seconds of this reaction?

5

Manganese oxide acts as a catalyst for the decomposition of hydrogen peroxide, what would be the effect of adding manganese oxide on the volume of oxygen produced by the end of this reaction (using the same amount of hydrogen peroxide)?

There would be no effect - the catalyst increases rate of reaction but doesn't increase overall product formed as it is not a reactant.

Manganese oxide acts as a catalyst for the decomposition of hydrogen peroxide, what would be the effect of adding manganese oxide on the volume of oxygen produced by the end of this reaction (using the same amount of hydrogen peroxide)?

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