2 What is combustion?a very rapid reaction of a substance with oxygen to produce compounds called oxides.FUEL + OXYGEN OXIDE + ENERGY
3 commonly referred to as burning easily identified by the production of heat (exothermic)type of synthesis reaction
4 RequirementsThree requirements for a combustion reaction
5 Fuels Gaseous Fuels Liquid Fuels Natural Gas/Methane - used for cooking, heating etc.Acetylene - used in welding, cutting etc.Liquid FuelsPetrol - used for internal combustion engines etc.Paraffin/kerosene - used in heating appliances etcAlcohols - used widely but includes preservatives, preparations, solvents etc.Oils - used for lubrication etc.
6 Fuels Solid Fuels The most common fuels are hydrocarbons Wood/paper/card.Plastics - most plastics will release toxic smoke during combustion.Metals - some metals are flammable, although usually very high temperatures are required.Foodstuffs - we actually 'burn' our food in order to cook it.The most common fuels are hydrocarbons
7 Complete CombustionComplete combustion of a hydrocarbon produces carbon dioxide gas and water vapour.Hydrocarbon + Oxygen Carbon dioxide + Watermethane + oxygen carbon dioxide + waterCH O2 CO H2O
8 Complete Combustion Complete combustions occurs when: Sufficient oxygen is presentTemperature is hot enoughComplete combustion is characterized by a blue flame. The flame is hotter than the flame of incomplete combustion.
9 Incomplete Combustion If insufficient oxygen is present, hydrocarbons burn to produce water vapour along with carbon monoxide, carbon dioxide and/or solid carbon.2CH O2 2CO + 4 H2OCH O2 C H2O
10 Incomplete Combustion Incomplete combustion is characterized by an orange or “dirty” flame.Produces black “soot” and the poisonous gas carbon monoxide
11 Time to Get to Work combustion animation Page 140 #19-24