Topic 7 - Organic Chemistry Flashcards
what is a hydrocarbon
a hydrocarbon is any compound that is formed from carbon and hydrogen atoms only
what is the simplest form of hydrocarbon
alkanes are the simplest form
what are alkanes (series, bonds)
they are a homologous series. they are saturated compounds with each carbon atom having four single covalent bonds.
what are the first four alkanes
methane: CH4 (little 4)
Ethane: C2H6 (little 4 and 6)
Propane: C3H8 (little 3 and 8)
Butane:C4H10 (little 4 and 10)
how does the properties of hydrocarbons change as the chains get longer
the shorter the chain the:
more runny consistency
more volatile (lower boiling point)
more flammable
what is complete combustion (process)
both carbon and hydrogen are oxidised
what is the waste product of complete combustion
carbon dioxide and water
how is crude oil made
it is made from fossil fuel. its formed from remains of dead plants and animals, mainly planktons, millions of years ago
what is crude oil a mixture of (mostly what)
it is a mixture of lots of different hydrocarbons, most alkanes. they are separated by fractional distillation
how does fractional distillation
oil heated and turned into gas. the gases enter fractionating columns
the higher you go the cooler the temperature is.
longer hydrocarbons have higher boiling points so they condense early on.
shorter hydrocarbons condense high up
how to crack longer hydrocarbons (heating)
you can crack them by thermal decomposition - breaking molecules down by heating them
what does it mean to split longer hydrocarbons
longer hydrocarbons don’t have many uses so you can split them into more useful oils like petrol
what are the steps to break down longer hydrocarbons
heat the chain up to vaporise them
vapor is passed over a hot powdered aluminum oxide catalyst
this is called catalytic cracking
