DF.5 Flashcards
Catalysis
What is energy density the measure of?
The amount of energy you get per kilogram or litre of fuel.
What is cracking?
A reaction where a large molecule is made into smaller molecules.
What is catalytic cracking?
Cracking in the presence of a catalyst.
What is a catalyst?
A substance that speeds up the reaction by providing an alternative reaction pathway with a lower activation enthalpy and is able to remain chemically unchanged at the end of the reaction.
What is the process of speeding up a chemical reaction using a catalyst called?
Catalysis.
Do the amount of catalyst used in the reaction have an impact on the amount of product formed at the end?
No, catalysts do not have an effect on yield, only the rate at which products are formed.
What are the two types of catalysis?
- Homogenous catalysis
- Heterogenous catalysis
When is the reaction said to involve homogenous catalysis?
When the reactants and the catalyst are in the same physical state.
When is the reaction said to involve heterogenous catalysis?
When the reactants and the catalyst are in different physical states.
Describe the four stages of heterogenous catalysis.
- Reactants form bonds with the surface of the catalyst, this is known as adsorption.
- As a result of bonds with the catalyst, bonds in reactants are weaken and eventually broken.
- New bonds form between reactants to form product.
- As a result of product bonds, bonds with catalyst surface weaken and break, releasing the product molecules, this is known as de-adsorption.
What are two key products of cracking?
Shorter alkanes and alkene.
Larger surface area of catalyst will have what effect on the reaction rate?
Increase reaction rate as there is larger surface area for contact with reactants.
What is a catalyst poison?
A substance that prevents the normal functioning of a catalyst, by adsorbing strongly to the catalyst surface and blocking it, causing it to be inactive.
