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Crude Oils

and fuels

QuestionAnswer
what gases do we get when we burn fuels? - carbon monoxide - nitrogen oxides - sulphur dioxide - particulates
what element do fossil fuels contain? sulphur
how do you get sulphur dioxide? when sulphur reacts with oxygen when we burn fuel
what problems are there with sulphur dioxide? - poisonous - acidic rain - causes engine corrosion
what is incomplete combustion? occurs when the supply of air or oxygen is poor. water is produced but carbon monoxide and carbon are produced instead of carbon dioxide
what are the problems with carbon monoxide? - poisonous - red blood cells pick up the gas and carry it around in your blood instead of oxygen
how is nitrogen oxide formed? high temperature inside a car engine makes nitrogen and oxygen react together
what are the problems with nitrogen oxide? - poisonous - acid rain - triggers people's asthma
what are particulates? diesel engines burn hydrocarbons with big molecules. these molecules react with oxygen. tiny particles containing carbon + unburnt hydrocarbons are produced
what substances are produced when hydrocarbons burn in air? water and carbon dioxide
why are short chain molecules the most useful? - make good fuels - are flammable - burn cleanly
what does viscous mean? thick don't flow easily
what is a hydrocarbon? a compound only made up of hydrogen and carbon atoms
what is an alkane? any of the series of saturated hydrocarbons e.g. methane, ethane, propane etc..
what is the general formula of an alkane? cnHx2n+2
why is crude oil referred to as an mixture? because it contains hydrocarbons of different chain lengths and these are separated into useful products. the fractions are not chemically bonded so it is a mixture
what problem does carbon dioxide cause? global warming
what problem does soot (particulates) cause? scientists think that when we breathe them in they damage our lungs and may cause cancer
what are greenhouse gases and what effect do they have? they collect in the atmosphere and reduce amount of heat loss by radiation from the earth's surface heating up the earth
why must we look for alternative fuels? because burning fossil fuels release a lot of greenhouse gases which is bad for the environment one day fossil fuels will run out alternative fuels will be renewable and sustainable
what does combustion mean? burning/reaction with oxygen
what does oxidised mean? combine or become chemically combined with oxygen
what is a biofuel? give 2 examples a fuel from a plant material or animal material e.g. ethanol and biodiesel
why are biofuels used?
small chain molecules have a low boiling point large chain molecules have a high boiling point
small chain molecules are not viscous large chain molecules are viscous
explain how crude oil is separated into fractions using the idea of different boiling points each hydrocarbon fraction contains molecules of similar amounts of carbon atoms. each fraction boils at different temperatures the tower is kept hot at the bottom (where crude oil is fed) its cooler at the top. the gases condense when they reach their BP
once the hydrocarbons have been collected what happens? they need refining before use
what does cracking mean? breaking down large hydrocarbon molecules into smaller more useful molecules
what is the process of cracking? cracking is the thermal decomposition reaction 1. heat the long shin hydrocarbon to vaporise it 2. vapour is passed over a powdered catalyst 3. the long chain molecules split apart/crack on the surface of the specks of catalyst
what is a catalyst? A catalyst is a substance that can increase the rate of a reaction. (speeds up chemical reactions)
what are the properties of an Alkane? - cnH2n+2 - single bonds - saturated
what are the properties of an Alkene? - cnH2n - double bond - unsaturated
how do you test for saturation and what is the result? add bromine water ALKENE-products are colourless ALKANE-no reaction, stays orange-yellow
what is a monomer? one small reactive molecule
what is a polymer? a long chain of monomers joined together
Created by: rv1
 

 



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