Organic Analysis

Cards (5)

  • Tests for Functional Groups:
    • Alcohols:
    • and alcohols are identified using acidified potassium dichromate, turning from orange to green if present
    • alcohols are not oxidised, and the potassium dichromate remains orange
    • Aldehydes:
    • Tollen’s reagent forms a silver mirror when added to the solution with an aldehyde present
    • Fehling's solution forms a brick red precipitate when heated if an aldehyde is present
    • Alkenes:
    • Bromine water changes from orange-brown to colorless in the presence of a carbon-carbon double bond
    • Carboxylic Acid - React with sodium carbonate to produce CO2, turning limewater cloudy if CO2 is present
  • Mass Spectrometry:
    • Used to identify compounds and determine their molecular formula
    • High Resolution Mass Spectrometry allows determination of Mr to several decimal places, precise atomic masses are given to calculate the molecular formula
  • Infrared Spectroscopy:
    • Uses infrared radiation to determine functional groups in organic compounds
    • Different bonds absorb radiation in varying amounts, allowing identification of functional groups
    • Characteristic peaks for different functional groups:
    • -OH Alcohol Group: 3230 - 3550 cm^-1
    • -OH Acid Group: 2500 - 3000 cm^-1
    • C=C Unsaturated Group: 1620 - 1680 cm^-1
    • C=O Carbonyl Group: 1680 - 1750 cm^-1
    • Fingerprint Region:
    • Contains tiny differences acting as a molecule's 'fingerprint' for identification
  • Infrared absorption in the atmosphere, like with ozone, traps heat causing global warming
    • Human activity releasing chemicals like CFCs enhances the heating effect, leading to global warming