Alkanes

• What is the main source of organic chemicals in the world?

  Crude oil
• Why is crude oil not very useful as a substance?

  It is a mixture of different hydrocarbons
• What are the useful components of crude oil called?

  Fractions
• How are fractions in crude oil separated?

  Based on boiling points
• What determines the fraction in which a hydrocarbon molecule will be separated?

  The size and length of the molecule
• What type of bonds do alkanes have?

  Only single bonds
• What is the role of the fractionating column in fractional distillation?

  To separate hydrocarbons based on boiling points
• Where are hydrocarbons with high boiling points collected in the fractionating column?

  Lower sections
• What happens to hydrocarbons with low boiling points in the fractionating column?

  They rise and condense at the top
• What can be produced when sulfur-containing compounds are burned?

  Sulfur dioxide
• What is cracking in the context of alkanes?

  Breaking down longer alkane chains into smaller ones
• What is crude oil primarily composed of?

  Alkanes, cycloalkanes, and arenes
• Why are smaller hydrocarbon fractions in high demand?

  They are more useful as fuels
• What is the result of cracking heavier fractions?

  Smaller alkanes and alkenes
• What conditions are required for thermal cracking?

  High temperatures and high pressure
• What is the temperature range for catalytic cracking?

  Around 450 °C
• What is produced mainly in catalytic cracking?

  Aromatic hydrocarbons
• What happens during complete combustion of alkanes?

  All carbon and hydrogen are oxidized
• What is produced during incomplete combustion of alkanes?

  Carbon monoxide and soot
• Where does incomplete combustion often occur?

  Inside a car engine
• What are the environmental consequences of car exhaust fumes?

  They damage nature and health
• What is carbon monoxide's effect on the body?

  It can cause dizziness and death
• How does carbon monoxide affect hemoglobin?

  It prevents binding of oxygen
• What reaction occurs in a car engine that produces nitrogen oxides?

  Nitrogen reacts with oxygen
• What is peroxyacetyl nitrate (PAN) associated with?

  Photochemical smog
• What is a consequence of acid rain?

  Corrosion of buildings and harm to life
• What are the steps involved in the fractional distillation of crude oil?

  1. Crude oil is heated in a fractionating column.
  2. Vapours rise and condense at different heights.
  3. Fractions are collected based on boiling points.
  4. Smaller hydrocarbons are collected at the top.
  5. Larger hydrocarbons are collected at the bottom.
• What are the two types of cracking and their conditions?

  • Thermal cracking:
  • High temperatures (up to 1000 °C)
  • High pressure (up to 70 atmospheres)
  • Catalytic cracking:
  • Lower temperature (around 450 °C)
  • Slight pressure with a catalyst
• What are the environmental impacts of combustion products from alkanes?

  • Carbon monoxide: toxic, causes health issues
  • Nitrogen oxides: contribute to smog and acid rain
  • Volatile organic compounds (VOCs): harmful to health and environment
• What are the main pollutants found in car exhaust fumes?

  • Carbon monoxide (CO)
  • Oxides of nitrogen (NO/NO2)
  • Volatile organic compounds (VOCs)
• What is the reaction of nitrogen with oxygen in a car engine?

  N (g) + O (g) → 2NO(g)
• Why does nitrogen react with oxygen in a car engine?

  High temperatures and pressures cause oxidation
• What do car exhaust fumes contain besides nitrogen oxides?

  Unburnt hydrocarbons and their oxides
• What is peroxyacetyl nitrate (PAN) formed from?

  Nitrogen oxides reacting with VOCs
• Why is PAN harmful?

  It harms lungs, eyes, and plant life
• How do nitrogen oxides contribute to acid rain?

  They react with water and oxygen to form nitric acid
• What are the effects of acid rain?

  Corrosion, endangerment of life, and health damage
• What is the purpose of catalytic converters in cars?

  To reduce pollutants in exhaust fumes
• What precious metal is commonly used in catalytic converters?

  Platinum
• What reactions occur in a catalytic converter?

  Oxidation of CO and reduction of NO