fuels Flashcards
how can impurities in some hydrocarbon fuels result in the production of sulfur dioxide?
Impurities in some hydrocarbons can lead to the result of production of sulfur dioxide, this is because when fuels are burnt, the sulfur is oxidised and turns into sulfur dioxide.
Explain some problems associated with acid rain caused when sulfur dioxide dissolves in rain water
When sulfur dioxide dissolves in rain water, it can turn into acid rain, acid rain can be bad as it makes it hard for crops to grow well as the soil can be too acidic, acid rain can in rivers and lakes can kill fish and insects and acid rain can prevent fish eggs from hatching. Acid rain can also increase the rate of weathering and break down the structure of buildings.
Explain why, when fuels are burned in engines, oxygen and nitrogen can react together at high temperatures to produce oxides of nitrogen, which are pollutants?
When fuels are burnt in engines, oxygen and nitrogen can react at high temps to produce oxides of nitrogen which are pollutants because car engines can be seen as internal combustion engines.
Evaluate the advantages and disadvantages of using hydrogen, rather than petrol, as a fuel in cars?
Advantages of using hydrogen as a fuel rather than petrol for a car is that:
hydrogen can be easily ignited and its combustion releases large amounts of energy.
Unlike petrol and other hydrocarbon fuels, the combustion of hydrogen produces only water vapour, no carbon dioxide.
This is good as carbon dioxide is a greenhouse gas and is linked to global warning and climate change.
A Disadvantage of hydrogen as a fuel is that it is a gas at room temperature meaning that it will be difficult to store it in large amounts.
Explain how cracking involves the breaking down of larger, saturated hydrocarbon molecules (alkanes) into smaller, more useful ones, some of which are unsaturated (alkenes)
Cracking:
Cracking involves breaking covalent bonds in hydrocarbon molecules.
E.g:
Octane(c8h18) —> Hexane(C6H14) + Ethene(C2H4)
Cracking can produce Hydrocarbons with double bonds which can be used as polymers.
Explain why cracking is necessary?
Cracking is necessary as it can be used to match supply with demand.
Explain why the alkanes are saturated hydrocarbons?
Alkanes= saturated hydrocarbons because their carbon atoms have only a single bond
Recall the formulae of molecules of the alkenes, ethene, propene, butene, and draw the structures of these molecules, showing all covalent bonds (but-1-ene and but-2-ene only)
Alkenes general formula= CnH2n
Ethene= C2H4
propene= C3H6
Butene= C4H8
Explain why the alkenes are unsaturated hydrocarbons, describing that their molecules contain the functional group C=C?
Alkenes= unsaturated because they have a double bond, the double bond in alkenes are known as the functional group as an alkenes double bond is mainly responsible for its chemical properties
Explain how bromine water is used to distinguish between alkanes and alkenes
Bromine water can be used to see if a product is an alkane or an alkene. When adding an alkene to bromine, the double bond removes the bromine and we end up with a colourless solution.
However there is no change when adding bromine water to an alkane.
Describe how the complete combustion of alkanes and alkenes involves the oxidation of the hydrocarbons to produce carbon dioxide and water?
When burning hydrocarbons, carbon dioxide and water are formed, during combustion, oxidation occurs. If all atoms in hydrocarbons are oxidised; the products are only water and carbon dioxide. This is complete combustion.
How can Combustion form Soot and Carbon Monoxide?
If there is a insufficient amount of oxygen, oxidation does not occur and carbon monoxide and soot can be formed. This is known as incomplete combustion.
Describe, using poly(ethene) as the example, that simple polymers consist of large molecules containing chains of carbon atoms
A polymer is a large molecule made from small monomers.
e.g
Polyethene is a large molecule formed when a large number of ethene monomers join together.
Describe some problems associated with polymers including the:
a availability of starting materials
b persistence in landfill sites, due to non-biodegradability
c gases produced during disposal by combustion
d requirement to sort polymers so that they can be melted and reformed into a new product
Problems of polymers:
A. Most of monomers needed to make synthetic polymers are obtained from crude oil. Crude oil is finite and non renewable. B. Polyethene is persistence in landfill sites because of its non-biodegradability, Its non-biodegradability means that microorganisms cannot break them down so they last for many years in landfill sites wasting space. C. When disposing polymers via combustion, carbon dioxide is produced which is not good as it is a greenhouse gas and is bad for the environment. D. The requirement of sorting polymers can also be very long as there are many steps,
Collect the waste
Sort the waste into different types of polymer
Dispose of waste that cannot be recycled in a landfill site
Clean polymers and grind them into chippings
Purify chippings
Melt Chippings then process them into a new product.
Evaluate the advantages and disadvantages of recycling polymers, including economic implications, availability of starting materials and environmental impact
Advantages of recycling polymers:
Reduces amount of waste that goes into incinerators or landfill sites
Helps conserve natural resources (crude Oil)
Disadvantages:
When recycling polymers, they can produce carbon dioxide which is a greenhouse gas
When recycling, toxic substances can be formed.
Toxic substances can be removed from the waste gases but they can produce toxic ash which must be disposed safely.
