organic chemistry Flashcards
what is crude oil and where is it found
a finite resource round in rocks
formed from ancient biomass (mainly plankton)
what do most compounds in crude oil consist of
carbon and hydrogen (hydrocarbons) most of which are alkanes
how do you separate crude oil into its compounds and why is this possible
fractional distillation
each compound has a different boiling point
explain how fractional distillation is used to separate crude oil into its compounds
- the oil is put into a chamber and is heated until most of it is a liquid
- this is then passed into a fractionating column where it is hotter at the bottom and gets cooler
- the hot gasses rise until they reach a region that is cooler than its boiling point where it condenses into a liquid
what are short chains of hydrocarbons used for
used to produce fuels such as petrol and diesel
what are petrochemicals and what are they used for
the substance’s from crude oil
used as feedstock
- lubricants, polymers, solvents, detergents
what are homologous series
a group of similar compounds with similar properties
what is the general formular for a hydrocarbon
Cn Hn+2
what are the first four hydrocarbons (alkanes) (names)
methane, propane, ethane, butane
what are the formulars for the first four hydrocarbons (alkanes)
CH4
C2H6
C3H8
C4H10
what is a saturated compound
organic compounds that have only one carbon to carbon single bond no double bonds
what are some properties of hydrocarbons. include boiling point, flammability etc
- boiling points increase as alkane gets longer
- the four first hydrocarbons are gasses
- the shorter the hydrocarbon the more volatile it is (likely to evaporate)
- the longer the more viscus
- shorter hydrocarbons are more flammable
what is the main use of a hydrocarbon
for fuel
how are hydrocarbons used for fuel
complete combustion
what is the equation for complete combustion with a hydrocarbon
hydrocarbon + oxygen —- co2 + water
what is the balanced equation for complete combustion of propane
C3H8 + 5O2 ——- 3CO2 + 4O2
what is the balanced equation for complete combustion of nonane
C9H20 + 14O2 —— 9CO2 + 10O2
what is cracking used for
breaking up the longer chains of hydrocarbons into smaller ones
what is a thermal decomposition reaction
breaking down molecules by heating
what are the two methods used for cracking
catalytic cracking and steam cracking
what is the first step of cracking for both steps
heating the long chain hydrocarbon and vaporise them
what does catalytic cracking use and what does this do
hot powdered aluminium oxide which the vapourised hydrocarbon will pass over splitting apart the hydrocarbon into two
what does steam cracking use and what does this do
steam which gets mixed into the vapourised hydrocarbon causing it to split into two smaller ones
what is the general balanced equation for the cracking of a long chain hydrocarbon
long chain hydrocarbon —– alkane + alkene
why is one product of cracking an alkene
each side of the equation needs to be equal with the same amount of hydrogens and carbons. after cracking, there will be the correct amount of carbon but not enough hydrogens and therefore must form a double bond becoming an alkene
Decane (C10H22) can be cracked into ethene ( C2H4) and one other hydrocarbon. write a balanced equation and find out the other product
C10H22 ——– ? + C2H4
need to be equal
10-2=8
22-4=18
? = C8H18
what is the general formular for an alkene
CnH2n
what are the first four alkenes
ethene, propene, butene, pentene
what are the formulars for the first four alkenes
C2H4
C3H6
C4H8
C5H10
what do all alkenes have and what does this make them (think structure)
at least one double bond - unsaturated
what are two differences of alkenes and alkanes
alkenes:
- are more reactive and therefore react with bromine
- they can be added together to make polymers
how are alkenes made into polymers
double bonds can break to form two more bonds
why can alkenes undergo addition reactions
they have a double bond which can open up and allow the two carbons to bond to atoms of other molecules
what are the three types of addition reactions with alkenes
hydrogen, water, halogens
explain what would happen in a reaction between propane and hydrogen
the double bond from the propane carbon atoms will break apart and the hydrogen atoms will be able to bond to the carbon. this forms the alkane propane which is now saturated
what is the condition needed in the reaction between propane and hydrogen
a catalyst