Organic analysis

• Structural isomer


  Compounds/molecules with the same molecular formula but a different structural formula
• Functional group


  An atom or group of atoms that give an organic compound its particular chemical properties
• Homologous series


  A family of organic compounds containing the same functional group and having the same general formula, but having a different carbon chain length, with each successive member differing by CH₂
• Empirical formula


  The simplest whole number ratio of atoms of each element in a compound/molecule
• Molecular formula


  The actual number of atoms of each element in a compound/molecule
• Structural formula


  Shows how the atoms in a molecule are arranged
• Displayed formula


  Shows all of the atoms and bonds in a molecule
• Skeletal formula


  Shows the shape of the carbon skeleton
• Isotopes


  Atoms of the same element (.e. have the same number of protons) with a different number of neutrons
• Functional group


  Alkenes<|>Primary and secondary alcohols<|>Aldehydes<|>Carboxylic acids<|>Halogenoalkanes
• Alkene reaction


  Alkenes react with Bromine water in an addition reaction
• Alcohol reaction


  1. Alcohols will act with sodium to produce a salt and hydrogen

  2. Primary and secondary alcohols can be oxidised by acidified potassium dichromate
• Aldehyde reaction


  1. Fehling's solution oxidises an aldehyde to a carboxylic acid

  2. Tollens' reagent reacts with an aldehyde to produce and silver mirror
• Carboxylic acid reaction


  Carboxylic acids will react with carbonates or hydrogencarbonates releasing CO2
• Halogenoalkane reaction


  Halogenoalkanes can be hydrolysed by warming with sodium hydroxide, the halide ion released can then be tested with silver nitrate solution
• Infrared spectroscopy


  Analytical technique used to identify types of organic compounds<|>Detects the presence of specific covalent bonds within a compound<|>Each type of bond vibrates at a specific frequency and so it absorbs a specific frequency of infra-red radiation<|>An infra-red spectrum is a graph of % transmittance against wave number (cm)<|>The position of each inverted peak/absorption tells us which bonds are present and therefore which functional groups are present in organic compounds
• There are two different absorptions for O-H bonds, they appear at slightly different wavenumbers and will be different sizes
• The fingerprint region below 1500cm-1 is unique to a compound, only a computer can compare fingerprint regions