ย 

Catalysts for Edexcel A-level Chemistry

Catalysts

This page covers the following topics:

1. Reaction profile
2. Arrhenius equation
3. Catalysts

Another type of graph can be used when assessing rate of reaction. This graph shows the energy available in the reactant particles and indicates the proportion of them that have the required energy for a reaction.

Reaction profile

To compare rate of reaction at different temperatures accurately the Arrhenius equation is used. A is the exponential factor, which relates to the frequency of particle collisions. K is the rate constant and is proportional to rate of reaction. ln is used to solve the Arrhenius equation to remove the 'e' from the equation, ln is a function on your calculator and you don't need to understand it further for chemistry.

Arrhenius equation

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

1

What factor would result in more reactant particles being present in the reaction space?

Increasing pressure or concentration

What factor would result in more reactant particles being present in the reaction space?

2

In the reaction between hydrogen and nitrogen at 40C the activation energy is 162 kJ/mol and the rate constant is 2.0 x 10-9 s-1. Calculate the exponential factor (A) for this experiment at 250K.

k is 2.96 x 10-16 s-1

In the reaction between hydrogen and nitrogen at 40C the activation energy is 162 kJ/mol and the rate constant is 2.0 x 10-9 s-1. Calculate the exponential factor (A) for this experiment at 250K.

3

What is the general mechanism of catalysis?

A transition metal will form a complex with the reagent undergoing oxidation or reduction to give or remove electrons as required. This elevates the reagent to a more reactive state so less energy is required for the reaction to take place.

What is the general mechanism of catalysis?

4

What is the term given to the required energy for a reaction?

Activation energy

What is the term given to the required energy for a reaction?

5

In the reaction between hydrogen and nitrogen at 50C the activation energy is 162 kJ/mol and the rate constant is 2.0 x 10-9 s-1. Calculate the exponential factor (A) for this experiment at 200K.

A is 3.17 x 1017 s-1

In the reaction between hydrogen and nitrogen at 50C the activation energy is 162 kJ/mol and the rate constant is 2.0 x 10-9 s-1. Calculate the exponential factor (A) for this experiment at 200K.

End of page

ย