crude oil - chemistry revision Flashcards
what is fractional distillation used for and how?
- it is used to seperate substances from crude oil
- the oil is heated on a furnace, and fed into a fractional column
what is the order of things in a fractioning column?
refinery gases - bottled gas
petrol - fuel for cars
kerosene - aircraft fuel
diesel - fuel for cars, lorries, buses
fuel oil - fuel for ships and power stations
bitumen - for roads and roofs
what are substances like at the top of the fractioning column?
- cooler
- smaller molecules
- very volatile (easily evaporated)
- flows easily (not viscous)
- ignites easily
what are substances like at the bottom of the column?
- hotter
- larger molecules
- high boiling point
- not very volatile (not easily evaporated)
- viscous (doesn’t flow easily)
- doesn’t ignite easily
what is the general formula for an alkane?
CnH2n+2
what is a hydrocarbon?
a compound of only hydrogen and carbon
what is the general formula of methane?
CH4
what are the formulas of hydrocarbons?
methane - CH4
ethane - C2H6
propane - C3H8
butane - C4H10
pentane - C5H12
what is homologous series?
a series of compounds which have:
- the same general formula
- differ by CH2 in molecular formula from neighbouring compounds
- show a gradual variation in physical properties e.g. boiling point
- have the same chemical properties
what is a saturated molecule?
a molecule that contains only single bonds
what is an isomer?
a molecule that have the same molecular formula but a different displayed one
what is complete combustion?
when there is a large supply of oxygen. the only products are carbon dioxide and water
what is incomplete combustion?
when there is insufficient oxygen. the products can be carbon monoxide, carbon dioxide or carbon, and water
what is the equation for complete combustion?
methane + oxygen —-> carbon dioxide + water
CH4 + 2O2 —> CO2 + 2H2O
what is the equation for incomplete combustion?
methane + oxygen —> carbon monoxide + water
CH4 + O2 —-> CO + 2H2O
what are the advantages of using hydrogen as fuel instead of petrol?
- clean
- only product is water
- releases more energy
- obtained from water (a renewable source)
doesn’t make carbon dioxide
what are the disadvantages of using hydrogen as fuel instead of petrol?
- expensive
- flammable
- not widely available
- there aren’t many hydrogen filling stations
what is cracking?
the breakdown of large hydrocarbons, to smaller more useful alkanes and alkenes
what is acid rain caused by?
caused by the release of sulphur dioxide (SO2) and nitrogen oxide into the atmosphere
nitrogen oxide (NO2) also creates smogs
how can acid rain affect the environment etc.?
it can hurt wildlife and harm the environment. it can get into rivers, poisoning fish and other sea creatures
how does acid rain occur?
when the sulphur dioxide mixes with oxygen in the air, and then they dissolve into the clouds creating acidic pollutions. as the clouds get heavy, they cause it to rain, releasing the acidic rain.
what oil is there a shortage of?
petrol
what oils are there a surplus of?
naptha, kerosene, gas oil and fuel oil
