Alkanes Flashcards
Why are alkanes unreactive?
1. C-C bonds and C-H bonds are very strong so cannot break easily yo form stronger bonds with other elements that easily
2. Have no polar side groups
What are the two main reactions that take place with alkanes?
1. Combustion
2. Reaction with halogens in the presence of UV light
Why are alkanes used as fuels?
They readily burn in air and are highly exothermic
What are the products of complete combustion?
Carbon dioxide and water
What steps are in the mechanism for Free Radical Substitution?
Initiation
Propagation
Termination
Do free radicals have a charge?
No
What is a free radical?
A highly reactive species which has one or more unpaired electrons
What kind of bond among many will be broken?
The weakest one
How do we terminate the presence of free radicals?
Reacting free radicals with other free radicals
What is a petroleum fraction?
A mixture of hydrocarbons of similar length within the same range of boiling point
How then are heavy residues from the fractionating column separated?
Distillation under a vacuum
Define cracking
The conversion of large hydrocarbon molecules into smaller hydrocarbon molecules by the breakage of C-C bonds.
What is produced from the cracking of alkanes?
Small chain alkane + Alkene + Hydrogen
What are the economic reasons for cracking?
1. Smaller chain alkanes are much more valuable than large chain alkanes
2. Smaller chain alkanes have more uses and are in higher demand as a result
What are the two types of cracking?
1. Thermal
2. Catalytic
