organic chem Flashcards
what is hydrocarbon
compound made of only hydrogen and carbon atoms
alkanes vs alkenes
alkanes have all c-c single bonds
alkenes have a double bone between two of the carbon atoms
alkane general formula
C n H 2n+2
what is a homologous series
group of organic compounds that react in a similar way to
why are alkanes suturated
each carbon atom forms 4 single covalent bonds
first four alkanes
methane
ethane
propane
butane
what happens if chain is longer
more intermolecular forces therefore:
• more viscous
• less flammable
• high boiling point
what are the waste products of complete compustion
co2 + h2o
complete combustion equation
hydrocarbon + oxygen —> co2 + h2o
what order do you balance complete combustion
c, h, o
what is crude oil and how do they form
a fossil fuel formed from the remains of dead plants & animals buried in mud
high temp and pressure turn remains to crude oil, drilld from rocks to obtain
are crude oils renewable
no
what is fractional distillation
separates all the different hydrocarbons (mostly alkanes) in crude oil
order of what gets condensed first in fractioning column
HDKPL
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Heavy fuel oil
Diesel oil
Kerosene
Petrol
LPG
how does fractional distillation work
• oil is heated and vaporised
• vapour enters fractioning columm
• column has temperature gradient
• longer HC have high BP, condense at bottom
• shorter HC have low BP, condense later on at top, just below BP
• each fraction had mixture of HC with similar numbers of BP & carbon atoms
two uses of crude oil
fuel
to make new compounds for things like polymers, lubricants
what is cracking
splitting long chain hydrocarbons
why is cracking necessary
• shorter HC are flammable so are fuel
• longer HC are thick like tar, not useful
• products can be useful fuels
cracking method
• cracking is thermal decomposition so is heated and vapourised
• vapour passed over hot powdered aluminium catalyst
• catalytic cracking: LC molecules split on surface of catalyst
• steam cracking: vapourise, mix w steam, heat.