Font size
WorksheetsCHROMATOGRAPHY
Total questions: 10
Worksheet time: 6mins
Chromatography usually involves two different phases. What names are given to these two phases?
Mobile and stationary
Soluble and insoluble
Solvent and solid
Wet and dry
Positive and negative
Why are chromatograms spotted with amino acid solutions often sprayed with ninhydrin after the chromatography is complete?
To make the spots visible on the paper
To stop the spots from moving further up the paper
To remove any impurities
To preserve the chromatogram for several years
To make the chromatogram safe to handle
A chromatography experiment was performed on five different solutions of amino acids (A–E). A contained cysteine, B contained glycine, C contained alanine, D contained valine, and E contained an unknown mixture of amino acids. By inspecting the chromatogram shown, which of the amino acids are present in solution E?
Glycine and valine
Cysteine and alanine
Alanine and valine
Cysteine and valine
Glycine and alanine
Shown below is a chromatogram of three unknown amino acids, A, B, and C, and a reference table of 𝑅f values of various amino acids. What are the three amino acids?
A: proline, B: lysine, C: glycine
A: glycine, B: alanine, C: proline
A: lysine, B: glycine, C: leucine
A: alanine, B: proline, C: lysine
A: leucine, B: alanine, C: lysine
A student is running a chromatography experiment. The diagram below shows their setup at the start of the experiment. What mistake has the student made?
The level of solvent is above the baseline.
The paper has not been sprayed with ninhydrin.
A lid has been placed over the beaker.
There is no thermometer to measure the temperature of the solvent.
The spots are not below the baseline.
The given chromatogram shows that substance B has traveled further up the chromatography paper than A. Which properties of a substance affect how far it will travel up the chromatography paper?
Its molecular weight and density
Its position in the reactivity series and reaction with water
Its boiling point and volatility
Its solubility in the solvent and attraction to the paper
Its color and pH
The 𝑅f value for valine is 0.60. If the solvent line was measured to have moved 4.0 cm from the starting point, how far from the starting point will a spot of valine have moved?
(a)
In a paper chromatography experiment, a student placed an ink mixture in a solvent beaker covered with a lid. He observed that the ink is not rising at all. Which of the following is the problem he encountered?
The mobile phase is not evaporating.
The ink is insoluble in the mobile phase.
The ink has high affinity with the mobile phase.
The mobile phase is evaporating.
The ink is soluble in the mobile phase.
A student is required to conduct a paper chromatography experiment to separate an unknown mixture. On a filter paper, he spotted two drops of the mixture on a line he drew using a pen. After that, he placed the paper on a solvent beaker and put a lid above the beaker. When his work was evaluated, he had points deducted because the results were not in the correct range. What mistake did he make?
Using a pen to draw the line
Using filter paper
Putting a lid on the beaker
Using a beaker
Adding two drops of the mixture
In TLC experiments, why is it important to place a lid over the solvent beaker?
To prevent air from entering the beaker
To preserve the chromatogram for several months
To protect the system from light
To prevent mobile phase evaporation
To prevent stationary phase evaporation
