Organic analysis

• What is the focus of the AQA A Level Chemistry study material?

  Organic Analysis
• What are the main methods for identifying functional groups in organic compounds?

  • Test-tube reactions
  • Mass spectrometry
  • Infrared spectroscopy
• Why do chemists need to identify functional groups in organic compounds?

  To understand the compound's chemical properties
• What does it suggest if a compound is acidic?

  It could be a carboxylic acid
• What does the state of a compound indicate about its structure?

  Solid suggests long C-C chains or strong forces
• What does it suggest if a compound is a liquid?

  It could suggest medium C-C chain length
• What does it suggest if a compound is a gas?

  It likely has very short C-C chain length
• What does water solubility indicate about a compound?

  It suggests the presence of polar groups
• What are test-tube reactions used for?

  To determine the functional groups present
• What is mass spectrometry?

  An analytical technique to identify unknown compounds
• How does mass spectrometry identify compounds?

  Molecules are bombarded with high energy electrons
• What happens to a molecule when it loses an electron in mass spectrometry?

  It forms a positively charged molecular ion
• What can the molecular ion do after formation?

  It can fragment to form new ions
• How are fragmented ions separated in mass spectrometry?

  By their mass to charge ratio
• What does an ion with mass 12 and charge 1+ have?

  An m/z value of 12
• What is the base peak in a mass spectrum?

  The peak corresponding to the most abundant ion
• What are isotopes?

  Atoms of the same element with different neutrons
• How can mass spectrometry be used with isotopes?

  To find the relative abundance of isotopes
• What does the relative abundance of an isotope indicate?

  The proportion of that isotope in nature
• How is the relative abundance shown in mass spectroscopy?

  By the heights of the peaks
• What is the relative abundance of Cl-35 and Cl-37?

  75% and 25% respectively
• What is the m/z ratio of an ion with mass 54 and charge 2+?

  $27$
• Which ion is deflected more in a mass spectrometer: Fe with mass 54 and charge 2+ or Fe with mass 56 and charge 3+?


  Fe with mass 54 and charge 2+
• What does the molecular ion peak indicate?

  The molecular mass of the compound
• What is the [M+1] peak in mass spectrometry?

  A peak due to carbon-13 isotope abundance
• How does the height of the [M+1] peak relate to carbon atoms?

  The more carbon atoms, the larger the peak
• What does a peak at m/z = 29 indicate in mass spectrometry?

  A characteristic fragment C₂H₅
• What do peaks at m/z = 18, 28, and 44 indicate?

  Loss of small molecules like H₂O, CO
• How can fragmentation help identify compounds in mass spectrometry?

  It reveals characteristic fragments of the compound
• What does the mass spectrum indicate if the molecular ion peak is at m/z = 70?

  The compound is likely pent-1-ene
• What does fragmentation in mass spectrometry involve?

  Breaking C-C bonds in molecules
• What is the m/e ratio sometimes referred to as?

  The m/z ratio
• What are the key points about the fragmentation of alkanes in mass spectrometry?

  • Simple alkanes fragment by breaking C-C bonds
  • m/e values of common alkane fragments are used for analysis
  • Fragmentation helps identify the structure of unknown compounds
• What are the characteristics of halogenoalkanes in mass spectrometry?

  • Often have multiple peaks around the molecular ion peak
  • Peaks indicate the presence of different isotopes or fragments
  • Useful for determining the structure of halogenoalkanes
• What is the molecular ion peak m/z value for pent-1-ene?

  70
• Why is the peak at m/z = 71 not considered the molecular ion peak?

  It is a C-13 peak
• What is the molecular mass of the C8H16 ion?

  70
• What is the molecular mass of the C4H8 ion?

  56
• How are simple alkanes fragmented in mass spectroscopy?

  • By breaking the C-C bonds
  • Produces various fragment ions
• What is a common peak observed in alcohol mass spectra?

  Peak at m/e value 31