Organic Analysis

• What can high resolution mass spectrometry determine?

  The molecular formula of a compound
• What does the peak with the highest mass/charge ratio represent?

  It represents the molecular ion
• What is the charge of the molecular ion in mass spectrometry?

  The charge is +1
• What does the mass/charge ratio equal in mass spectrometry?

  It equals the relative molecular mass (Mr)
• What does mass spectrometry detect in organic molecules?

  Whole molecules and their fragments
• What is the molecular formula of butane?

  C4H10
• What is a molecular ion?

  A molecule with one electron knocked off
• How many decimal places can high resolution mass spectroscopy measure?

  Four decimal places
• Why is high resolution mass spectroscopy useful?

  It differentiates compounds with similar Mr
• What is the accurate mass of hydrogen (H)?

  1.0078
• What is the accurate mass of carbon (C)?

  12.0000
• What is the accurate mass of oxygen (O)?

  15.9949
• What is the accurate mass of nitrogen (N)?

  14.0031
• What molecular formula corresponds to Mr = 60.02112?

  C2H4O2
• What molecular formula corresponds to Mr = 60.05751?

  C3H8O
• What molecular formula corresponds to Mr = 60.03235?

  CH4N2O
• What is the Mr of CH3CH2OH calculated to four decimal places?

  46.0417
• What is the Mr of H2NCH2NH2 calculated to four decimal places?

  46.0530
• What is the standard reference value for carbon?

  12.0000
• What happens when a compound contains chlorine or bromine atoms?

  Two molecular ion peaks will occur
• What are the isotopes of chlorine and their relative abundances?

  Cl35 (75%) and Cl37 (25%)
• What are the isotopes of bromine and their relative abundances?

  Br79 (50%) and Br81 (50%)
• What is the m/z value of CH3Cl?

  M = 50
• What is the m/z value of CH3Br?

  M = 94
• What is the ratio of heights for CH3Cl's M:M+2 peaks?

  3:1
• What is the ratio of heights for CH3Br's M:M+2 peaks?

  1:1
• What is the m/z value of C2H4Cl2?

  M = 98
• What is the ratio of heights for C2H4Cl2's M:M+2:M+4 peaks?

  9:6:1
• What is the m/z value of C2H4Br2?

  M = 186
• What is the ratio of heights for C2H4Br2's M:M+2:M+4 peaks?

  1:2:1
• What is the m/z value of C2H3Cl3?

  M = 132
• What is the ratio of heights for C2H3Cl3's M:M+2:M+4:M+6 peaks?

  27:27:9:1
• What is the purpose of infrared spectroscopy?

  To identify types of bonds in a molecule

  
• What is the fingerprint region in infrared spectroscopy?

  Below 1500 cm-1
• What is the significance of the fingerprint region?

  It is unique for every compound
• How is the fingerprint region used in spectroscopy?

  To identify compounds against a database
• What is the range for functional group identification in infrared spectroscopy?

  Above 1500 cm-1
• What is the absorption range for C=O bonds?

  1680 – 1750 cm-1
• What is the absorption range for O-H (acid) bonds?

  2500 – 3000 cm-1
• What indicates the presence of a C=O bond in butanal's spectrum?

  An absorption between 1680-1750 cm-1