Catalysts

Question 1

What is a catalyst?

Answer 1

A catalyst increases the rate of a chemical reaction without being used up in the process.
—> May react to form an intermediate.
—> May provide a surface on which the reaction can take place.
—> Is later regenerated, so does not undergo any permanent change so is always in the correct orientation.

Question 2

How does a catalyst affect activation energy?

Answer 2

A catalyst lowers activation energy of the reaction by providing an alternative route with a lower activation energy.

Question 3

What is a homogenous catalyst?

Answer 3

A homogenous catalyst has the same physical state as the reactants.

Question 4

What is a heterogenous catalyst?

Answer 4

A heterogenous catalyst has a different physical state from the reactants.
—> Reactant molecules are ABSORBED onto the surface of the catalyst.
—> Product molecules leave the catalyst by DESORPTION.

Question 5

How do catalysts help to reduce energy consumption and the environment?

Answer 5

1. • Catalysts significantly speed up the process by lowering the activation energy of the reaction.
   • This means less energy is needed, so this saves on energy costs as less crude oil is burnt.
2. • If less crude oil is burnt then less carbon dioxide is released into the atmosphere.

Question 6

What is the economic importance of catalysts?

Answer 6

1. Products can be made more quickly, requiring less energy, cutting fuel costs and reducing waste,
2. Catalytic converters improve air quality by reducing toxic emissions and preventing petrochemical smog.
3. Break the triple bond in the nitrogen during the Haber process which requires lots of energy , so an iron catalyst is used to reduce the activation energy by weakening the nitrogen bond.

Question 7

How do catalysts act as biological enzymes?

Answer 7

1. Can lead to the formation of a single pure product (specificity).
2. Operate under mild conditions, such as low temperatures, atmospheric pressures and at an optimum pH.

Question 8

What are the benefits of the use of enzymes in industry?

Answer 8

• Lower temperatures and pressures can be used.
• Pure products are usually formed so complex separation techniques are not needed, reducing costs.
• Enzymes are biodegradable.
• Have many industrial uses, eg. Food and drink production, detergents, textiles and leather.