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TYpes of Chemical Reactions

TYpes of Chemical Reactions. Part 3. Types of REactions. Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions Combustion Corrosion. combustion. Combustion is the chemical reaction in which fuel “burns” or reacts quickly with oxygen

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TYpes of Chemical Reactions

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  1. TYpes of Chemical Reactions • Part 3

  2. Types of REactions • Synthesis Reactions • Decomposition Reactions • Single Displacement Reactions • Double Displacement Reactions • Combustion • Corrosion

  3. combustion • Combustion is the chemical reaction in which fuel “burns” or reacts quickly with oxygen • The products of this reaction are usually an oxide and energy Sunrise Propane Explosion Toronto 2008

  4. Hydrocarbons • Hydrocarbons (HC) are a group of compounds that only contain the elements carbon and hydrogen • Example: Propane, C3H8 • HC originate from fossil fuels • The combustion of HCs power cars & buses, warm homes, generate electricity & light candles

  5. Complete combustion of Hydrocarbons • Products of HC combustion can vary - depend on availability of oxygen • Plentiful oxygen = complete combustion • Complete combustion of HC: • hydrocarbon + oxygen → CO2 + H2O + energy • CO2 is an important green house gas - more in climate change unit!

  6. complete combustion of hydrocarbons • The balanced chemical equation for the complete combustion of hydrocarbons can be represented by the general equation: • CxHy + O2 → CO2 + H2O + energy • During complete combustion, fuel burns clean with no sooty residue

  7. Incomplete combustion of hydrocarbons • If oxygen supply is limited, incomplete combustion may occur • Results in release of carbon monoxide gas and carbon (soot) in addition to carbon dioxide and water • An orange flickering flame indicates incomplete combustion

  8. Carbon Monoxide (CO) • Carbon monoxide is a colourless, odorless gas • Highly toxic • Symptoms of poisoning - headaches, dizziness, nausea, respiratory problems • Cause of many deaths - incomplete combustion in confined space • Carbon monoxide detectors!

  9. soot • Made up of particles of carbon • Causes pollution and wastes energy • Common in older vehicles with poorly maintained engines • Common result of forest fires

  10. Other combustion reactions • Many substances (besides HC) undergo combustion • Elements react with oxygen to form oxides • General equation: element + oxygen → oxide + energy • Eg. magnesium burns to form magnesium oxide + energy

  11. Corrosion • Is the breakdown of metal as a result of chemical reactions with the environment

  12. beneficial corrosion • Example: aluminum exposed to air • Corrodes to form aluminum oxide - one of the hardest substances known • Aluminum oxide tightly coats underlying metal, preventing further corrosion • Application - camping pans

  13. rust • Familiar reddish-brown flaky material produced when metals containing iron corrode • Rust does not stick well to underlying steel • Readily flakes away so fresh steel is exposed to further corrosion • Continues until steel is completely eaten away!

  14. rust • Causes of rust: • Oxygen • Water • Electrolytes - not a cause, but speeds up corrosion once it starts

  15. Preventing corrosion • Protective Coatings • Cover metal with rust inhibiting paint, chrome or plastic coating • Corrosion still possible with chips/scratches • Corrosion resistant materials • Plastic - Eg. car bumpers • Corrosion resistant alloys (blend of metals) - Eg. surgical knee implant

  16. Galvanizing • Galvanized steel is steel coated with thin layer of zinc • Zinc corrodes before steel • Zinc corrodes to form protective oxide layer

  17. Demo of the day! • Time for some combustion in action! • Combustion of acetylene • 2C2H2 (g) + 5O2 (g) → 4CO2 (g) + 2H2O(g)

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