UV-Visible Spectroscopy Technique Characteristics
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Questions and Answers

What is the purpose of using a filter in colorimeters and filter photometers?

  • To measure radiant power directly
  • To increase the sensitivity of the measurement (correct)
  • To decrease the sensitivity of the measurement
  • To employ a diffraction grating for measurement

    • What is the definition of a chromophore?

  • A type of colorimeter
  • A sample that does not absorb light
  • A functional group that absorbs radiant energy in the UV or visible regions (correct)
  • An instrument used for UV-Vis spectroscopy

    • What does UV-Vis spectroscopy primarily measure?

  • How much light is reflected off a sample
  • The color of a chemical substance
  • How much a chemical substance absorbs light (correct)
  • The refractive index of a material

    • Why are derivatives formed in UV-Vis spectroscopy usually conjugated?

    <p>To increase the molar absorptivity value</p> Signup and view all the answers

    In which spectral region does UV-Vis spectroscopy operate?

    <p>Ultraviolet-visible</p> Signup and view all the answers

    Why can UV-Vis spectroscopy be used in the presence of interfering substances?

    <p>Fewer compounds absorb in the visible region</p> Signup and view all the answers

    What is the primary function of the collimating lens in the monochromator unit?

    <p>To collimate the light</p> Signup and view all the answers

    Which type of monochromator is commonly used in modern UV/VIS spectrometers?

    <p>Grating monochromator</p> Signup and view all the answers

    What is the primary function of the exit slit in the monochromator unit?

    <p>To allow the corrected wavelength of light to reach the sample cuvette</p> Signup and view all the answers

    What is the main advantage of a grating monochromator over a prism monochromator?

    <p>Grating monochromators are more effective in converting polychromatic light to monochromatic light</p> Signup and view all the answers

    What is the primary function of the focusing lens in the monochromator unit?

    <p>To capture the dispersed light and sharpen it to the sample cuvette</p> Signup and view all the answers

    Which material is often used for the prism in a UV spectrum monochromator?

    <p>Quartz or Fused Silica</p> Signup and view all the answers

    What does the Beer-Lambert law relate?

    <p>The absorbance of light to the concentration of a solution</p> Signup and view all the answers

    What is the unit of the molar extinction coefficient (ε) in the Beer-Lambert law equation?

    <p>M^-1 cm^-1</p> Signup and view all the answers

    What is a cause of nonlinearity in the Beer-Lambert law at high concentrations?

    <p>Deviations in absorptivity coefficients due to electrostatic interactions</p> Signup and view all the answers

    If a plot of absorbance versus concentration is linear, what does it indicate?

    <p>The Beer-Lambert law is obeyed</p> Signup and view all the answers

    What is the symbol used to represent the path length in the Beer-Lambert law equation?

    <p>L</p> Signup and view all the answers

    What is the condition for the Beer-Lambert law to be valid?

    <p>The solution must be dilute and homogeneous</p> Signup and view all the answers

    What type of radiation is typically used in NMR spectroscopy?

    <p>Radiofrequency radiation</p> Signup and view all the answers

    What happens when the frequency of the RF radiation matches the nuclei's resonance frequency in the magnetic field?

    <p>The nuclei absorb energy and shift to a higher energy level</p> Signup and view all the answers

    What is the purpose of the receiver in NMR spectroscopy?

    <p>To detect the emitted radiation from the nuclei</p> Signup and view all the answers

    Which of the following nuclei are commonly observed in NMR spectroscopy?

    <p>H, C, N, F, Si, and P</p> Signup and view all the answers

    Why is NMR spectroscopy considered a relatively insensitive technique?

    <p>The net energy absorption by the population of low energy protons in the sample is low</p> Signup and view all the answers

    What is the primary advantage of NMR spectroscopy compared to other techniques?

    <p>It provides much more information about molecular structure</p> Signup and view all the answers

    What is the primary function of IR spectroscopy?

    <p>To analyze how molecules interact with infrared light</p> Signup and view all the answers

    Which type of covalent bonds are primarily observed in IR spectroscopy?

    <p>Polar covalent bonds</p> Signup and view all the answers

    What type of molecular vibrations are involved in IR spectroscopy?

    <p>Stretching and bending vibrations</p> Signup and view all the answers

    Which region of the electromagnetic spectrum is utilized in IR spectroscopy?

    <p>Infrared light</p> Signup and view all the answers

    Which phase(s) of matter can be analyzed using IR spectroscopy?

    <p>Solids, liquids, and gases</p> Signup and view all the answers

    What is a primary application of IR spectroscopy?

    <p>Identification of functional groups</p> Signup and view all the answers

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