topic 7 - organic chemistry Flashcards
hydrocarbon
compound formed with only hydrogen and carbon atoms
formula for alkanes
CnH2n+2
properties alkanes
- saturated
- shorter the chain the less viscous (more running)
- shorter the chain the lower the boiling point
- shorter the chain the more flammable
first 4 alkanes
- methane
- ethane
- propane
4 . butane
complete combustion of any hydrocarbon
hydrocarbon + oxygen –> carbon dioxide + water
- releases huge amounts of energy - used as fuels
- both carbon and hydrogen from the hydrocarbon are oxidised
crude oil
- fossil fuel
- formed from remains of plants and animals that died billions of years ago particularly plankton
- contains lots of different hydrocarbons with different properties
fractional distillation’s temp gradient
- hotter at the bottom and cooler at the top
- longer chain hydrocarbons have higher boiling points so condense to liquids at the bottom
- shorter chain hydrocarbons have lower boiling poinst and so condense at the top later on
order of things that make it to the top of fractional distillation
TOP:
1. petrol
2. kerosene
3. diesel oil
4. heavy fuel oil
BOTTOM:
uses of oil
- fuel for transport
- polymers
- solvents
- lubricants
- detergents
catalytic cracking VS steam cracking
thermal decomposition reaction
CATALYTIC: heat hydrocarbon to gas and pass over hot powdered aluminion oxide catalyst
STEAM: heat hydrocarbon to gas and mix with steam at very high tempertaures
whats an alkene
- double bond
- unsaturated
- reactive bc double bond can open and react
first 4 alkenes
- ethene
- propene
- butene
- pentene
alkene formula
CnH2n
alkenes in incomplete combustion
alkene + oxygen —> carbon + carbon monoxide + carbon dioxide + water
- smokey yellow flame and less energy released
alkenes functional group
C=C