Fuels
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what happens to a combustion reaction when the concentration of oxygen increases
the combustion reaction will become more vigorous
what is a fuel
a fuel is usually a substance which burns (reacts with oxygen) to give out energy
what is burning
burning is a chemical reaction with oxygen, in which energy is released (mainly heat) Combustion is another name for burning - a reaction which gives out heat is exothermic
what three things are needed for a combustion reaction
fuel, oxygen and heat
describe the difference between complete and incomplete combustion
complete combustion = plentiful supply of oxygen incomplete combustion=restricted supply of oxygen
what are the products of complete and incomplete combustion with a hydrocarbon
complete combustion = CO2 + H20/water incomplete combustion = C02 + C + H20 + C0
what is the test for incomplete combustion?
holding a white tile above the flame, if it is incomplete combustion the soot/carbon from the flame will make the tile black
how are coal, oil and natural gas made?
coal - ancient plant material oil, gas - ancient marine life material burried underground under intense heat and pressure caused the carbon to to compress
why are fossil fuels described as non renewable
they cat be replaced within a human life time
state the 2 main issues from burning fossil fuels
1) releases CO2, greenhouse gas 2) C02 + H20 = acid (acid rain + acidification of oceans)
order and use of fractions of fractionally distilled crude oil (top to bottom)
gases - BBQs, Camping Petrol - car fuel naptha - medicine, making plastic kerosine (parafin) - aviation fuel diesel - truck/bus fuel oil , wax - engine oil, candle bitumen/residue - roads
what technique is used to seperate the compounds within crude oil
fractional distilation
what is crude oil
crude oil is a mixture of many different liquids and dissolved gases mostly containing hydrocarbons
what is viscosity
viscosity is how freely a substance flows, the more viscous something is the slower it will flow
what is volatility
volatility is how easy something evaporates, the more volatile the easier it evaporates
explain the chemical properties in terms of viscosity, volatility, flamability and size of molecule in each fraction of crude oil
first fraction - least viscous, most volatile, smallest molecule, most flammable last fraction- most viscous, least flammible, largest molecule, least volatile
what happens to (and why) to the boiling and melting point of a molecule as it lengthens
the boiling point and melting point will increase due to the inter molecular forces becoming stronger.
why is raw crude oil no use?
too many different compounds with different chemical properties in crude oil.
what is meant by a fraction
a portion of crude oil with similar boiling points
what is catalytic cracking
catalytic cracking is the process by the oil industry to break up large alkane molecules into smaller more useful molecules
what is the formula to work out energy
Eh = cmΔT c- heat capacity (water, 4.18) m - mass (water) in Kg ΔT - change of temp
what is the formula to find ΔT
ΔT = Eh ——— c x m
what is the formula to find m
m = Eh ———- ΔT x C
what is the formula to find C
C = Eh ———- ΔT x M