crude oils and fuels Flashcards Preview

Chemistry GCSE > crude oils and fuels > Flashcards

Flashcards in crude oils and fuels Deck (44):

what is crude oil a mixture of


compounds that only contain hydrogen and carbon - joined together by covalent bonds

most are alkanes


what is the general formulae for the family of alkane hydrocarbons


eg methane = CH(4)
ethane = C(2)H(6)


draw methane as an alkane molecule displayed formulae


covalent bonds =straight line
atom is shown as its symbol


name the alkanes in order of smallest to biggest



what type of hydrocarbons are alkanes

saturated hydrocarbons

means contain as many hydrogen atoms as possible in each molecule

no more hydrogen atoms can be added


what's a saturated hydrocarbon

carbon atoms are joined together by single bonds

makes them unreactive
apart from boring or combustion which is their reaction with oxygen in the air


what is distillation

process used to separate pure liquid from a mixture of liquids

works when liquids have different boiling points

heats(evaporates)> cools (condenses)


how is fractional distilation different to normal distillation

different from distilation cause it separates mixture into different parts called fractions


how does fractional distillation work

1. crude oil is heated to evaporate

2. crude oil fed at bottom of a tall Column as hot vapour

3. hot at bottom cool at top, several condensers coming off at different heights

4. gases condense when they reach their boiling points

5. different fractions are collected as different liquids at different levels

boils/condenses at different temperatures cause of different sizes of molecules


what has the lowest boiling points

Petrol , refinery gas (shorter carbon atoms)


what has the highest boiling points

bitumen, oil (longer carbon atoms)

cool to form very thick liquids or solids at room temperature


what are properties of short chain alkanes

low boiling point

less viscous( more runny)

more volatile(more likely to turn into a gas)

more flammable (easier it burns)


what are the properties of long chain alkanes

high boiling point

more viscous( less runny)

less volatile(less likely to turn into a gas)

less flammable (harder it burns)


where is crude oil derived from

biomass found in rocks, over millions of years


what comes out of the bottoms of fractional distillation Collums


very thick, mixture of long-chain hydrocarbons, used in making roads and flat roof


what happens when the fractions have been collected

they need more processing before they can be used


are the long chain atoms near the bottom of the top in fractional distillation

substances with higher boiling points (long chain) condense at bottom and lower boiling points (short chain) condense at least he top

each fraction contains hydrocarbon molecules with a similar number of carbon atoms


what are lighter fractions used for and why?

used a fuels

because when they burn in plenty of air they release energy

called oxidised (meaning adding oxygen in a chemical reaction in which the oxides are formed)

propane+ oxygen > carbon dioxide+ water


how can we test that carbon Dixie is produced in combustion

limewater goes cloudy


how can you tell that water is produced in combustion

blue colbalt paper goes from blue to pink


how is selfie dioxide produced

impurities containing sulphur is a product of fuels being burnt as fuels.

sulphur reacts with oxygen when we burn the fuel- creating sulphur dioxide


what is sulphur dioxide and what does it do

poisonous gas


causes acid rain

can cause engine corrosion


what is incomplete combustion and when does it happen

when there isn't enough oxygen

instead of carbon dioxide being produced carbon monoxide is produced


why is carbon monoxide poisonous

red blood cells pick it up and carry it around the blood instead of oxygen

even small amounts of carbon monoxide can be bad for you


how are nitrogen oxides formed

high temperatures in an engine allow nitrogen and oxygen to form nitrogen oxides.


what is nitrogen oxide


can trigger asthma attacks

cause acidic rain


what is particulates

tiny solid particles containing carbon and Unburnt hydrocarbons

get carried into the air

scientists think they damage our lungs and might cause cancer


how are particulates produced

in Diesel engines

hydrocarbons are burnt with much bigger molecules

big molecules react with oxygen and don't always burn completely - particulates are produced


what does carbon dioxide do

main greenhouse gas in the air

absorbs energy released as radiation from surface of the earth

causes global warming, increased world's temperature.


what do particulates do

tiny solid particles made from carbon and Unburnt hydrocarbons

travel into the upper atmosphere, reflecting sunlight back into space- causing global dimming


what does carbon monoxide do

affects the amount of oxygen that our blood is able to carry

particularly serious for people who have heart problems


what does sulfur and nitrogen oxides do

make people suffer from asthma because of increased air pollution

cause acid rain because they dissolve in water droplets in the atmosphere
and react with oxygen creating sulphuric and nitric acids

rain with a low oh can damage plants and animals


what's a catalytic converter

catalytic converters in car exhausts- reduces carbon monoxide and nitrogen oxides produced

expensive because they contain precious metal catalysts- but are very effective

do not help reduce levels of carbon dioxide


how do catalytic converters work

metal catalysts arranged so they have a large surface area

causes carbon monoxide and nitrogen oxides to react together and produce nitrogen and carbon dioxide

carbon monoxide + nitrogen oxide> carbon dioxide + nitrogen


what do filters do

remove most particulates from the modern diesel engines.

the filets need to burn off trapped solid particulates otherwise they will get blocked


how is sulfur dioxide removed in power stations

removed from flue (waste) gases by reacting it with calcium oxide or calcium hydroxide.

sulfur é impurities can also be removed from fuel before the fuel is burned (happens in cars and factories)


so have can you reduce the effects of burning fuel

1. catalyst converters

2. filters

3. reacting sulphur with calcium oxide/calcium hydroxide

4. removing sulphur from fuel before burning fuel


what's a biofuel

fuels made from plant or animal products


what's a biodiesel

fuel for cars made from plant oils


what are the advantages of biodiesel a

1. cheaper than petrol and diesel - crude oil price going up

2. carbon neutral

3. it's renewable and reliable

4. makes other useful producers eh high energy food for goes and soap


what does carbon neutral mean

the amount of carbon dioxide given off when it burns is balanced by the amount absorbed as plants it is made from grow


What are the disadvantages of biodiesels

1. freezes before traditional diesels and can turn into sticky goo at high temperatures in a engine

2. can destroy habitats- large areas of tropic forest are being cut down and turned into Palm oil plantations for biodiesel- orangutans habitats destroyed

3. used late areas of farmland where food could be produces. food becomes too expensive in poorer countries and people die


what happens in complete combustion with hydrocarbons

the carbon in the hydrocarbons oxidises to carbon dioxide

the hydrogen oxidises to water

but needs to be plenty of air!!


what is exothermic

a type of energy that releases energy from a fuel