Presentation on theme: "Fuels A Fuel is a substance that produces Energy when burned."— Presentation transcript:
1 Fuels A Fuel is a substance that produces Energy when burned. A good fuel releases it’s energy over a longer period of timeA reaction in which energy is released is called an Exothermic reaction( a reaction in which heat is taken in called an Endothermic reaction).Another word for burning is Combustion ie.we combine the element with Oxygen gas
2 Common fuels Most common household fuels contain the element Carbon. Fuels that contain carbon and hydrogen only are called Hydrocarbons.The simplest hydrocarbon is methane formula CH4.Methane makes up 96% of Natural Gas.
3 Combustion of Hydrocarbons Carbon dioxide is collected in the tube here. The test for CO2 is that it turns limewater Milky(or chalky)Combustion of Methane gasWater vapour from the burning methane gas condenses hereAll Hydrocarbons burn to give CO2 and H2OIn fact any substance that contains Carbon and Hydrogen gives CO2 and H2O when burned
4 Fossil FuelsFossil Fuels are formed from Living things millions of years ago. There are three main Fossil Fuels:Coal, Oil and GasGas was formed in much the same way as Oil.It is often collected when drilling for Oil.Fossil Fuels are Finite Fuels ie.They will run out in the future and cannot be regeneratedCoal: This was formed by the decay of Vegetation which was subjected to heat and pressure over a very long period of timeOil: This was formed by dead sea creatures falling to the sea-bed where they were subjected to chemical change by BacteriaAlternative sources of Energy which are Renewable must be found eg. Solar, Wind Tide and Wave Power
5 Distillation of Crude Oil Crude Oil is a mixture of Substances called Fractions.To separate the fractions we heat them until they boil off. This is known as Fractional DistillationThe smaller fractions ie short carbon chains have smaller Boiling Pts. and boil off first.The smaller fractions are more flammable, lighter in colour and less Viscous than the longer chain FractionsA Fractionating Tower
6 Air PollutionWhen Carbon burns in plentiful supply of air it produces CO2C + O2CO2When Carbon burns in an insufficient supply of oxygen it produces ` Carbon MonoxideC + O2COCO is an odourless, poisonous gas which prevents the blood absorbing Oxygen is therefore extremely dangerousThe test for CO2 is that it turns limewater milky(chalky)CO2 extinguishes fires, whereas CO burns with a blue flame. CO is neutral whereas, CO2 is Acidic
7 Pollution from Cars The main pollutants from car exhausts are Unburned HydrocarbonsCarbon MonoxideOxides of Nitrogen occurs in the Spark Plugs of petrol cars (not Diesel since they do not have spark plugs)Cars have Catalytic Converters fitted to change these to harmless gases CO2 and N2. Catalytic converters are metal honeycombs coated in PlatinumSulphur from petrol produces the acidic gas Sulphur Dioxide(also a pollutant)when burned