organic chemistry

• What is crude oil primarily composed of?

  A mixture of hydrocarbons
• Why is crude oil heated in the process of fractional distillation?

  To evaporate all of the compounds from liquid to gas
• What happens to the gaseous hydrocarbons as they rise up the fractionating column?

  They cool down
• Why do hot gases rise in the fractionating column?

  Because hot gas rises
• What occurs when hydrocarbons cool down below their boiling point in the fractionating column?

  They condense into liquid hydrocarbons
• Where do the liquid hydrocarbons collect in the fractionating column?

  In trays
• Why do longer chain hydrocarbons condense at the bottom of the fractionating column?

  Because they have high boiling points
• Where do shorter chain hydrocarbons condense in the fractionating column?

  At the top of the column
• Why do shorter chain hydrocarbons condense at the top of the fractionating column?

  Because they have much lower boiling points
• catalytic cracking

  • First, some long chain alkanes are heated until they vaporise into a gas
  • Then they're passed over a hot, powdered aluminium oxide catalyst 
  • This breaks the long chain alkanes into a small chain alkane and an alkene
• What is crude oil?

  A mixture of compounds from ancient biomass
• Why is crude oil considered a finite resource?

  It cannot be replaced as it is used up
• What is a hydrocarbon?

  A compound made of hydrogen and carbon
• What are alkanes?

  Saturated hydrocarbons with formula CnH2n+2
• What defines a homologous series?

  Compounds with same formula and properties
• Describe the combustion of hydrocarbons.

  • Exothermic reaction with oxygen
  • Complete combustion: produces CO2 and water
  • Incomplete combustion: produces carbon or CO and water
• Describe the physical properties of alkanes.

  • First few are gases, then liquids, then solids
  • Boiling points and viscosity increase with size
  • Volatility and flammability decrease with size
  • Generally poor reactivity
• Explain how fractional distillation of crude oil takes place.

  • Crude oil is heated and vaporized
  • Vapor rises in a fractionating column
  • Column is hotter at the bottom, cooler at the top
  • Hydrocarbons condense at different heights
  • Large molecules collected at the bottom
  • Small molecules collected at the top
• What is cracking?

  Thermal breakdown of large hydrocarbons
• What type of reaction is cracking?

  Thermal decomposition
• What are the conditions for cracking?

  Heated vapor over a catalyst or steam
• How are the products of cracking used?

  • Alkanes and alkenes produced
  • Used as polymers
  • Starting materials for synthesis
• What is an alkene?

  Unsaturated hydrocarbon with a C=C bond
• What is the general formula for alkenes?

  CnH2n
• What is the test for alkenes?

  Add bromine water; color changes to colorless
• Describe the combustion of alkenes.

  • Burns with smoky flames
  • Due to incomplete combustion
• Describe addition reactions of alkenes.

  • Atoms added across the C=C bond
  • Hydrogenation: requires nickel catalyst
  • Hydration: requires H3PO4 catalyst
  • Addition of halogens: Br2/Cl2/I2
• What is an alcohol?

  Organic compound with an -OH group
• State characteristics of methanol, ethanol, propanol, and butanol.

  • Dissolve in water to form neutral solution
  • React with sodium to produce hydrogen
  • Burn in oxygen
  • React with carboxylic acids to form esters
• What does oxidation of alcohols lead to?

  Formation of carboxylic acids
• What are some uses of alcohols?

  • Fuels
  • Solvents
  • Drinks
• What are the conditions required for fermentation of glucose?

  • 30 degrees Celsius
  • Aqueous glucose solution
  • Absence of air
  • Yeast added
• What is the equation for fermentation of glucose?

  C6H12O6 → 2 CH3CH2OH + 2 CO2
• What are carboxylic acids?

  Organic compounds with a COOH group
• State characteristics of carboxylic acids.

  • Dissolve in water to form acidic solution
  • Contains H+ ions
  • React with metals
• What are the conditions required for fermentation of glucose?

  30 degrees Celsius, aqueous glucose, absence of air, yeast
• What is the equation for the fermentation of glucose?

  C$_6$H$_{12}$O$_6$ → 2 CH$_3$CH$_2$OH + 2 CO$_2$
• What are carboxylic acids?

  Organic compounds containing a COOH functional group
• What are the characteristics of carboxylic acids?

  • Dissolve in water to form acidic solutions
  • React with metal carbonates to produce CO$_2$
  • React with alcohols to form esters with acid catalyst
  • React with metals to release hydrogen gas
• What type of acid is a carboxylic acid?

  It is a weak acid