Combustion Reactions

Oxidation

• when molecules react with oxygen

• very reactive metals cause highly exothermic and rapid reactions

• moderately reactive metals have slow exothermic reactions

• when metals react with oxygen, a basic metal oxide is formed:

• metal + oxygen —> metal oxide

• e.g. magnesium + oxide —> magnesium oxide

Oxidation Reaction with Non-Metals

• non-metals thay react with oxygen form covalent bonds

• e.g. C + O2 = CO2

• reactions can produce a flame and is classified as a combustion reaction

Combustion of Hydrocarbons

• When pure hydrocarbons burn in unlimited oxygen, carbon dioxide and water are produced:

  Hydro carbon + oxygen → carbon dioxide + water

• when pure hydrocarbons burn in limited oxygen, carbon monoxide (co) and water are produced:

  Hydrocarbon + limited oxygen → carbon motoxide + cater

  • carbon monoxide is a poisonous gas that binds tightly to haemoglobin in red blood cells (more tightly than O2)

  • fatal as it starves the brain and other tissues of oxygen

  When pure hydrocarbons burn in minimal oxygen, unburnt carbon (soot) and water are produced:

  Hydrocarbon + minimal Oxygen → carbon + water

Combustion Reactions

• all involve oxygen (O2) as a reactant, combining with another substance.

• all combustion reactions are exothermic

most common fuels used for combustion are compounds of carbon and hydrogen (hydrocarbons)

Types of Hydrocarbons

Methane (CH4)

Ethane (C2H6)

Propane (C3H8)