C1.5 Fuels Flashcards
What is fractional distillation?
Separating crude oil into different length hydrocarbons.
What is crude oil?
A mixture of different length hydrocarbons that is found in the ground. It is a fossil fuel.
What is a fraction?
A fraction contains hydrocarbons of similar length that have one function.
What are the order of fractions starting with the shortest chain hydrocarbon?
Gases Petrol Naphtha Kerosene Diesel Fuel oil Bitumen
What are sone properties if short chain hydrocarbons?
More flammable
Less viscous
What is complete combustion?
When hydrocarbons burn with enough oxygen, to produce only carbon dioxide.
What is the word equation for complete combustion?
Hydrocarbon + Oxygen -> Carbon dioxide + Water
What is incomplete combustion?
When hydrocarbons burn without enough oxygen to produce carbon, carbon monoxide, carbon dioxide and water.
What is the word equation for incomplete combustion?
Hydrocarbon + oxygen -> Carbon + Carbon monoxide + Carbon dioxide + Water
Why is incomplete combustion a problem?
It produces toxic carbon monoxide - which is colourless, odourless and extremely toxic.
What factors should you consider when choosing a fuel?
Ease of ignition
Energy value
Ash and smoke produced
Storage and transport ease.
Why can burning fossil fuels be a greater problem for the environment?
They contain sulphur impurities. This is released into the air as sulphur dioxide.
Why is sulphur dioxide in the air a problem?
It combines with clean clouds to form acid clouds which rain acid rain.
What are the problems caused by acid rain?
It causes lakes to become acidic which kills the animals and plants
It kills trees
It destroys limestone buildings and statues.
What can be done about the sulphur impurities in fuels?
It can be removed in the fuel before it is burnt - but this is expensive, uses energy and makes the fuel lose energy
Power stations use acid gas scrubbers to remove harmful gases before they release their emissions
Cars have catalytic converters.
Why are greenhouse gases bad in too high concentrations in the atmosphere?
They act as an insulating layer and radiate heat from the sun back to earth rather than letting it escape.
How does human activity affect Carbon dioxide levels?
When we burn things, we release ‘locked up’ carbon dioxide back into the atmosphere.
What is iron seeding?
When iron is injected into the ocean to encourage photosynthesis and the growth h of phytoplankton. They absorb carbon dioxide from the atmosphere.
What are the problems with iron seeding?
Some plankton may be toxic and grow in large numbers
Dead zones are created in the ocean where nothing can live as the microorganisms that decompose the plankton use up all the oxygen.
What is another way that carbon dioxide can be removed from the atmosphere?
Scientists are researching if waste carbon dioxide can be turned into more useful hydrocarbons. This would only work if the energy used for this process was green energy.
What are the two main types of biofuels?
Biogas
Ethanol
What is biogas?
Biogas is a gas created by microorganisms when they decompose living organisms waste or dead plants.
What are the uses of biogas?
It can be burned to heat water for central heating systems.
It can power a turbine ti produce electricity
It can also be a fuel for cars and buses
What are the advantages of biogas?
It is renewable
It is carbon neutral
It is fairly clean and has very few sulphur impurities or produce oxides of nitrogen
The raw materials are very cheap.
What are the advantages of using ethanol as a fuel?
Less crude oil is used
It is carbon neutral
What are the disadvantages of using ethanol as a fuel?
It takes up lots of land to grow the sugar to make ethanol
Less land for food
Lots of energy needed for distillation of ethanol.
What is a fuel cell?
A fuel cell is an electrical cell thats supplied with a fuel and oxygen and uses energy from the reaction between them to generate electricity.
Why were fuel cells developed?
As part of the space programme. They were more practical than solar cells and less dangerous than nuclear power.
What are the advantages of using hydrogen-oxygen fuel cells to power cars?
No moving parts so no energy is lost through friction.
No pollutants are produced
What are some advantages of hydrogen fuel cells?
They are more efficient than power stations.
Less stages so less energy is lost as heat.
They do not produce conventional pollutants.
They could replace batteries, which contain toxic metal compounds.
How can you measure the energy content of a fuel?
By using a calorimeter.
How do you carry out a calorimetric experiment?
Put fuel into a spirit burner and weigh the burner full of fuel
Measure some water into a copper calorimeter
Take the initial temperature of the water
When the water has risen in temperature by 20-30 degrees, blow out the burner and take the highest temperature of the water
Reweigh the burner and fuel.
What three things do you need to consider to keep a calorimetric experiment the same?
Same apparatus
Same volume of water
The water should start and finish at the same temperature.
What are alkanes?
Single bond hydrocarbons that are saturated.
Why do alkanes not turn bromine water brown and do not form polymers?
They have no spare bonds.
What is the generic formula for carbon and hydrogen in an alkane?
C = n H = 2n+2
What is an alkene?
An unsaturated hydrocarbon with a double bomd.
Why can alkenes form polymers and turn bromine water colourless?
They have spare bonds.
What are the first four alkanes or alkenes?
Meth-
Eth-
Prop-
But-
What is cracking?
The thermal decomposition of long chain hydrocarbons into shorter chain hydrocarbons.
Why are some hydrocarbons cracked?
If there is a greater demand for those hydrocarbons.
Why is cracking important industrially?
It produces alkenes, which can be made into plastics.
What is always produced in cracking?
Alkanes or alkenes
