Topic 7- organic chemistry

• 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 of hydrogen and carbon atoms
• 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
• What are 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 occurs.

  • 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?

  As alkanes and alkenes 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
• How do alkenes combust?

  They burn with smoky flames
• Describe addition reactions of alkenes.

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

  An 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?

  Carboxylic acids
• What are some uses of alcohols?

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

  30°C, aqueous glucose, absence of air, yeast
• 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
  • React with metal carbonates to produce CO2
  • React with alcohols to form esters
  • React with metals to release hydrogen gas
• What type of acid is a carboxylic acid?

  It is a weak acid
• Why are carboxylic acids considered weak acids?

  Partially dissociated in water
• What is an ester and how is it formed?

  Organic compound with -COO- group from acid and alcohol
• What is a polymer?

  A long chain molecule from smaller molecules
• How do C=C bond molecules form polymers?

  • C=C bonds open up
  • Smaller molecules (monomers) join together
  • No other products are made
  • Called addition polymerisation
• What is a repeating unit of a polymer?

  Smallest structure yielding polymer's structure
• What is a condensation polymer?

  Polymer made in condensation polymerisation
• What is an amide bond?

  Similar to ester bond, with O replaced by N
• What is an amino acid?

  Organic compound with COOH and -NH2 groups
• How do amino acids make proteins?

  • Through condensation polymerisation reactions
  • Proteins are polymers of amino acids
  • Polypeptides are shorter chains of amino acids
• What are carbohydrates?

  Organic molecules made of C, H, and O
• What is DNA and its role?

  • Material that makes up chromosomes
  • Stores genetic information
  • Made of two polymer chains in a double helix
  • Composed of nucleotides