7.2.1 Principles of IR Spectroscopy

    Cards (18)

    • What is infrared (IR) spectroscopy used for?
      Identify functional groups
    • IR spectroscopy is based on the ability of molecules to absorb specific frequencies of infrared radiation
    • The O-H (Alcohol) functional group absorbs in the range of 3200-3600 cm1cm^{ - 1}.
    • What are the wavelength boundaries of the IR region in the electromagnetic spectrum?
      700 nm - 1 mm
    • Molecules can vibrate in two primary ways: stretching and bending
    • Each type of bond in a molecule has unique vibrational frequencies.
    • What is the frequency range of the IR region in the electromagnetic spectrum?
      300 GHz - 400 THz
    • IR spectroscopy helps identify functional groups by analyzing molecular vibrations
    • What is the wavelength range of microwaves in the electromagnetic spectrum?
      1 mm - 30 cm
    • Stretching vibrations involve the lengthening or shortening of chemical bonds along the bond axis.
    • What does infrared (IR) spectroscopy identify in a compound?
      Functional groups
    • Infrared (IR) spectroscopy identifies functional groups based on their characteristic absorption frequencies
    • Different functional groups absorb IR radiation at the same frequencies.
      False
    • Match the functional group with its characteristic absorption range in cm^{ - 1}</latex>:
      O-H (Alcohol) ↔️ 3200-3600
      C=O (Carbonyl) ↔️ 1650-1750
      N-H (Amine) ↔️ 3300-3500
    • Arrange the steps in interpreting an IR spectrum:
      1️⃣ Identify characteristic peaks
      2️⃣ Determine wavenumbers
      3️⃣ Analyze peak intensities
      4️⃣ Assign peaks to functional groups
    • What does wavenumber measure in an IR spectrum?
      Radiation frequency
    • The O-H bond in alcohol produces a broad peak in the IR spectrum.
    • The C=O bond in a carbonyl group produces a strong peak in the IR spectrum at approximately 1650-1750 cm1cm^{ - 1}.Strong
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