Chromatography: Stationary Phases
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Questions and Answers

What is the chemical formula of silica gel?

  • SiO4
  • SiO3
  • SiO2 (correct)
  • SiO

    • How does the polarity of silica gel compare to alumina?

  • Silica gel is less polar than alumina. (correct)
  • Silica gel is more polar than alumina.
  • Silica gel and alumina have the same polarity.
  • Silica gel has no polarity, while alumina is polar.

    • What type of adsorbent is silica gel?

  • Acidic adsorbent (correct)
  • Basic adsorbent
  • Non-adsorbent
  • Neutral adsorbent

    • Which compounds does silica gel preferentially retain?

    <p>Basic compounds</p> Signup and view all the answers

    What is the relationship between the polarity of silica gel and its adsorption properties?

    <p>The lower the polarity of silica gel, the better it can adsorb basic compounds.</p> Signup and view all the answers

    What type of interactions does the compound exhibit?

    <p>Dipole-dipole and H-bonding</p> Signup and view all the answers

    How do polar analytes interact with the stationary phase in TLC?

    <p>They interact strongly with the stationary phase</p> Signup and view all the answers

    Why do polar analytes move very slowly up the TLC plate?

    <p>Due to strong interactions with the stationary phase</p> Signup and view all the answers

    Which type of bonding is most likely responsible for the slow movement of polar analytes up the TLC plate?

    <p>Hydrogen bonding</p> Signup and view all the answers

    What effect do dipole-dipole interactions have on the movement of polar analytes in TLC?

    <p>Slows down their movement</p> Signup and view all the answers

    What are the 2 most common adsorbents used in chromatography?

    <p>Porous alumina and porous silica gel</p> Signup and view all the answers

    Which material is NOT commonly used as an adsorbent in chromatography?

    <p>Activated charcoal</p> Signup and view all the answers

    Which of the following is a common misconception about chromatography adsorbents?

    <p>Activated carbon is one of the 2 most common adsorbents</p> Signup and view all the answers

    Why are porous alumina and porous silica gel commonly used as adsorbents in chromatography?

    <p>They provide a high surface area for adsorption</p> Signup and view all the answers

    What is a key advantage of using porous alumina and porous silica gel in chromatography applications?

    <p>They provide good resolution due to their selectivity</p> Signup and view all the answers

    Which statement is true about the mobile phase in thin-layer chromatography (TLC)?

    <p>The mobile phase is relatively nonpolar.</p> Signup and view all the answers

    How do nonpolar analytes interact with the components of a TLC plate?

    <p>They interact weakly with the polar silica gel and strongly with the nonpolar mobile phase.</p> Signup and view all the answers

    What happens to nonpolar analytes on a TLC plate?

    <p>They move higher up the TLC plate.</p> Signup and view all the answers

    Which of the following is true about the interaction between analytes and the components of a TLC plate?

    <p>Polar analytes interact more strongly with the polar silica gel.</p> Signup and view all the answers

    What is the purpose of using a relatively nonpolar mobile phase in TLC?

    <p>To increase the separation of nonpolar analytes on the TLC plate.</p> Signup and view all the answers

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