combustion of alkanes

• What is the general reactivity of alkanes?

  Alkanes are generally unreactive
• Why are alkanes relatively unreactive?

  Due to their non-polar nature and strong covalent bonds
• What is the electronegativity difference between carbon and hydrogen in alkanes?

  The difference is minimal
• What does the minimal electronegativity difference in alkanes lead to?

  Almost equal sharing of electrons
• What makes it difficult for alkanes to attract nucleophiles or electrophiles?

  The lack of significant partial charges
• What are the main reactions that alkanes undergo?

  • Combustion: Reaction with oxygen to release energy
  • Substitution: Replacing H atoms with halogens in light presence
• What is the role of alkanes in combustion reactions?

  They serve as efficient fuels
• What do alkanes release when burnt?

  A significant amount of energy
• In what applications are alkanes used due to their energy release?

  Power generation, heating, and transportation
• What are the two types of combustion reactions alkanes can undergo?

  • Complete combustion
  • Incomplete combustion
• What happens during complete combustion of alkanes?

  They form carbon dioxide and water vapour
• What is the equation for the complete combustion of methane?

  CH4(g) + 2O2(g) ➔ CO2(g) + 2H2O(g)
• What are key points regarding the combustion of alkanes?

  • Alkanes must be vaporised before combustion
  • Smaller alkanes combust more readily
  • Larger alkanes release more energy per mole
• What occurs during incomplete combustion of alkanes?

  Carbon monoxide and water vapour are formed
• What is the equation for the incomplete combustion of methane?

  CH4(g) + 3⁄2O2(g) ➔ CO(g) + 2H2O(g)
• What additional products can result from incomplete combustion?

  Solid carbon (soot) and unburnt hydrocarbons
• What are the environmental impacts of burning alkanes?

  • Releases pollutants into the environment
  • Contributes to respiratory issues
  • Causes global warming and climate change
• What are carbon particulates created from?

  Incomplete combustion as soot
• What issues do carbon particulates cause?

  Respiratory issues and engine damage
• What is carbon monoxide produced from?

  Incomplete combustion
• How does carbon monoxide affect the body?

  Inhibits oxygen transportation by binding with haemoglobin
• What are the symptoms of carbon monoxide exposure?

  Blurred vision, poor coordination, and headaches
• What greenhouse gas is produced during complete combustion?

  Carbon dioxide
• How does carbon dioxide contribute to climate change?

  By absorbing and emitting infrared radiation
• What is the greenhouse effect?

  Process of trapping heat in the Earth's atmosphere
• What are unburnt hydrocarbons a by-product of?

  Incomplete combustion
• Why are some unburnt hydrocarbons concerning?

  Some are carcinogenic and cause smog
• What do unburnt hydrocarbons react with to produce photochemical smog?

  Nitrogen oxides in sunlight
• How are nitrogen oxides generated?

  When nitrogen and oxygen react at high temperatures
• What is the equation for nitrogen oxides formation?

  N2(g) + O2(g) ➔ 2NO(g)
• How do nitrogen oxides contribute to environmental issues?

  They form photochemical smog and acid rain
• What happens when nitrogen dioxide dissolves in water?

  It forms nitric acid, lowering rainwater pH
• What is the equation for nitrogen dioxide reacting with water?

  2NO2(g) + H2O(l) + 1⁄2O2(g) ➔ 2HNO3(aq)
• What is sulfur dioxide formed from?

  Oxidising sulfur impurities in fossil fuels
• What happens to sulfur dioxide in clouds?

  It oxidises into sulfuric acid
• What is the main component of acid rain?

  Sulfuric acid
• What technologies are used to reduce emissions from burning alkanes?

  • Catalytic converters
  • Flue gas desulfurisation
• What is the purpose of catalytic converters?

  To remove pollutants from vehicle exhaust
• What structure do catalytic converters contain?

  A honeycomb structure coated with catalyst metals
• What do catalyst metals in catalytic converters do?

  Catalyse conversion of harmful compounds