alkanes Flashcards
define an alkane
saturated hyrocarbon
what is petroleum
a mixture consisting mainly of hydrocarbons that can be separated by fractional distillation
alkanes general formula
CnH2n+2
effect of increasing carbon chain lengths on alkanes
boiling point increases due to number of electron increases and stronger IDD forces
effect of increasing branching in alkanes
the boiling point decrease as number of electrons stays same and there is less surface contact and weaker IDD forces
alkanes are the main constitute in
crude oil
process from separating crude oil into seperate molecules
fractional distillation as the different chain lengths results in them having boiling points
1. the mixture is vaporized and fed into fractionating column
2. very hot near the base but cooler near the top
3. when passed into tower, near the bottom, the vapors rise cool and condense
4. products are siphoned off for different uses
define cracking
breaking C-C bonds producing small molecules from larger molecules
thermal cracking
this method produced a high proportion of alkanes and alkenes, high temperatures and high pressures required
catalytic cracking
this method mainly used to produce motor fuels and aromatic hydrocarbons
takes place at slight pressure and high temperature and in presence of zeolite catalyst
explain the economic reasons for cracking alkanes
small chain molecules are in more high demand than larger chain molecules
alkanes are used as
fuels
combustion of alkanes can be
complete or incomplete
complete combustion of alkane
alkanes + exess oxegon –> carbon dioxide + water
incomplete combustion of alkanes
alkane +limiting oxegon –> carbon monoxide + water
