Worksheet: Thin-Layer Chromatography

In this worksheet, we will practice describing thin-layer chromatography methods, selecting mobile phases and methods for staining or detecting fractions.

Q1:

When separating a solid mixture by thin-layer chromatography, which of the following steps is not required?

  • AThe solid is dissolved in an organic solvent.
  • BMovement of the solvent front is accurately timed.
  • CA spot of solution is applied to the plate.
  • DThe base of the upright plate is immersed in an organic solvent.
  • EMovement of the solute spots is accurately measured.

Q2:

A reaction mixture is analyzed by thin-layer chromatography before (A) and after (B) a reaction takes place, using a silica TLC plate and a 201 mixture of hexane and ethyl acetate. In the diagram showing the TLC plate, the positions of the separated fractions are marked as spots between the baseline (solid line) and solvent front (dashed line).

Which spot corresponds to the product of the reaction with the highest polarity?

Which spot corresponds to the limiting reactant in this reaction?

Estimate the 𝑅f value of fraction 5, to 1 significant figure.

Q3:

The stationary phase in ion exchange chromatography (IEC) is a cross-linked polymer resin with covalently attached functional groups. Which of the following is not a typical functional group used for IEC?

  • AHydroxyl (OH)
  • BCarboxylate (COO)
  • CSulfonate (SO3)
  • DQuarternary ammonium (CHN(CH)233+)
  • EAmmonium (NH3+)

Q4:

Fill in the blank: Ion exchange chromatography is best suited to separate .

  • Ahydrophobic molecules
  • Bcations and anions
  • Chydrophilic molecules
  • Dlarge molecules, such as DNA and RNA
  • Emixed metal sulfides and oxides

Q5:

Which of the following statements about the mobile phase in supercritical fluid chromatography (SFC) is false?

  • AIt has the solvent properties of a liquid.
  • BIt requires lower pressures than those needed for HPLC.
  • CIts mobile phase has the viscosity properties of a gas.
  • DIt gives better resolution than GC.
  • EIt has densities similar to a liquid.

Q6:

Which of the following gases is not a common carrier gas for gas chromatography?

  • AOxygen
  • BHelium
  • CNitrogen
  • DArgon
  • ECarbon dioxide

Q7:

Which of the following GC detectors would most likely allow recovery of a sample after analysis?

  • AThermal conductivity detector (TCD)
  • BNitrogen–phosphorus detector
  • CFlame ionization detector (FID)
  • DFlame photometric detector (FPD)
  • EHall electrolytic conductivity detector

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.