Organic chemistry

• What are hydrocarbons composed of?


  Hydrogen and carbon atoms
• How do the melting and boiling points of hydrocarbons compare to inorganic compounds?


  They have low melting and boiling points compared to inorganic compounds
• What happens when hydrocarbons are burned?


  They are combustible, releasing energy
• What determines the physical state of hydrocarbons?


  Their molecular size
• What is an example of a gaseous hydrocarbon at room temperature?


  Methane (CH₄)
• What type of hydrocarbons are alkenes?


  Unsaturated hydrocarbons
• What is the key difference between alkanes and alkenes?


  Alkenes have at least one double bond, while alkanes have only single bonds
• Why are alkenes more reactive than alkanes?


  Due to their double bond
• What is the first step in the fractional distillation of crude oil?


  Heating the crude oil to about 350°C
• What happens to the vapor in the fractional distillation column?


  It enters a tall column that is hot at the bottom and cooler at the top
• How do different hydrocarbons condense in the fractional distillation process?


  Lighter fractions rise higher and condense at lower temperatures, while heavier fractions condense at higher temperatures lower in the column
• What are the key fractions collected from fractional distillation from top to bottom?


  Gases, petrol, kerosene, diesel oil, fuel oil, bitumen
• What is the purpose of cracking in the petrochemical industry?


  To break down larger hydrocarbon molecules into smaller, more useful ones
• What are the two methods of cracking?

  Thermal cracking and catalytic cracking
• What is the temperature used in catalytic cracking?


  About 500°C
• What are the products of cracking?


  Smaller alkanes and alkenes
• What is an example reaction of cracking?


  C₁₀H₂₂ → C₂H₄ + C₈H₁₈
• Why is cracking economically significant?


  It helps meet demand for lighter fractions and valuable chemicals
• What are the two main uses of hydrocarbons?


  As fuels and as raw materials for producing polymers
• What is a concern regarding many polymers produced from hydrocarbons?


  They are non-biodegradable, leading to plastic pollution
• What is the main component of petrol?

  Octane (C₈H₁₈)
• What is liquefied petroleum gas (LPG) primarily composed of?


  Propane (C₃H₈) and Butane (C₄H₁₀)
• How do hydrocarbons contribute to climate change?


  By releasing CO₂ when burned
• What is the role of alkenes in the production of plastics?


  They serve as key raw materials for producing polymers
• What is crude oil made from?

  Stabilized plankton
• Why is crude oil considered non-renewable?

  It is formed from ancient organic matter
• What are hydrocarbons primarily composed of?

  Hydrogen and carbon
• What is the characteristic of long-chain hydrocarbons?

  They are less flammable and more viscous
• What is the chemical formula for propane?

  C3H8
• What is the chemical formula for butane?

  C4H10
• What is the chemical formula for pentane?

  C5H12
• What is the chemical formula for hexane?

  C6H14
• What is the chemical formula for heptane?

  C7H16
• What is the chemical formula for octane?

  C8H18
• What is the chemical formula for nonane?

  C9H20
• What type of hydrocarbons are alkanes?

  Saturated hydrocarbons
• What is the general formula for alkanes?

  CnH2n+2
• What do alkanes produce when burned?

  Carbon dioxide and water vapor
• What is the composition of the Earth's atmosphere in terms of nitrogen?

  78%
• What is the composition of the Earth's atmosphere in terms of oxygen?

  21%