2.5 Developing Fuels

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2.5 Developing Fuels
Cracking ­ any reaction in which a larger molecule is made into smaller molecules
Cracking reactions can vary. Some types of cracking are:
Alkanes branches alkanes + branched alkenes
Alkanes Smaller alkanes + cycloalkanes
Cycloalkanes alkenes + branched alkenes
Alkenes smaller alkenes
In catalytic cracking, a zeolite catalyst is
used. Zeolites tend to produce straight
chain hydrocarbons as they have holes in
their structure not big enough for long
branches to fit through.
Carbon forms on the catalyst surface rendering it
The catalyst needs to be regenerated to overcome this.
Catalyst ­ a substance which lowers the activation energy of a reaction in order to speed it up and is
able to be recovered, chemically unchanged, at the end.
Catalysis ­ The process of speeding up a chemical reaction using a catalyst
Homogenous catalysts
If the reactants and the catalyst are in the same physical state the catalyst is said to be homogenous.
Enzymes are examples of this as all the reactants and the enzymes are in solution in the cells.

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Heterogeneous catalyst
The reactants and catalyst are in different physical states. This
usually involves gas or liquid reactants and a solid catalyst.
(1) The reactants are adsorbed onto the surface of the catalyst.
As a result, bonds in the reactants are weakened.
(2) The weakened bonds in the reactant molecules break and
new bonds are made to form the products. This is because the
reactants are all held close together on the catalyst's surface.…read more

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Naming Alkenes…read more


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