TOPIC 7 ORGANIC CHEMISTRY Flashcards
what is a hydrocarbon
one that contains hydrogen and carbon atoms only
what bond do alkanes always have
C-C Single bonds
general formula of hydrocarbons
CnH(2n+2)
n is small and so is 2
what are the first 4 alkanes
-methane
-ethane
-propane
-butane
draw methane ehtane propane butane bonds
state how the length changing of a hydrocarbon effects the carbon chain
-shorter the carbon chain,
- more runny a hydrocarbon is (less viscous it then is)
-more volatile (lower boiling points)
-more flammable
complete combustion equation
hydrocarbon + oxygen —- carbon dioixde + water
what are the waste products in complete combustion
carbon dioxide
water vapour
what is crude oil
a fossil fuel formed from the remains of plants and animals
-mainly plankton
state 3 non renewable fuels
-coal
-oil
-gas
what can be done to seperate hydrocarbon fractions
-fractional distillation
state how to seperate hydrocarbon fractions
- oil is heated until its turned into gas. + then enters a fractionating column
- in column a temp gradient (hot at bottom and gets cooler as you go up)
- longer hydrocarbons have high boiling points which means they will condense back into liquids and drain out the column early on
- end up with crude oil mixture seperated out into different fractions
state crude oils uses in modern day life
-oil provides fuel for most transport e/g cars, trains, planes
-petrochemical industry used it as feedstock to make new compounds like polymers, solvents
what does cracking mean
splitting up long chain hydrocarbons
a charactersistic of short chain hydrocarbons
long chain ones
short
-are flammable so make good fuels + are high in demand
long
-form thick gloopy liquids like tar
different methods of cracking
-heat long chain hydrocarbons to vaporise them
-vapour is then passed over hot powdered aluminium oxide catalyst
-long chain molecules split apart on the surface
