An ancient manuscript has been recovered, and historians want to determine its origin.
A sample of the inks from the manuscript is sent to a laboratory for thin-layer chromatography (TLC) analysis to compare them with reference inks used in the 1400s and the 1800s.
The chromatograms are shown below:
Look at the chromatogram for the sample of the inks from the manuscript. Which ink colour(s) is/are pure?
The black, blue, and red inks from the manuscript are tested with three different solvents, P, Q, and R. The solubility results are shown below:
| Ink colour | Solvent P | Solvent Q | Solvent R |
|---|---|---|---|
| Black | Clear black solution | Black solid left in tube | Clear black solution |
| Blue | Clear blue solution | Blue solid left in tube | Clear blue solution |
| Red | Clear red solution | Red solid left in tube | Red solution with some red solid left in tube |
Which solvent, P, Q, or R, should the laboratory use for the thin-layer chromatography? Explain why this solvent is better than the others.
Scientists use RfR_fRf values to compare the different spots on a chromatogram.
Calculate the RfR_fRf value for the top spot of the black ink in the sample from the manuscript.
- The distance from the baseline to the solvent front is 8.0 cm8.0\text{ cm}8.0 cm.
- The distance from the baseline to the centre of the top spot for the black ink is 6.2 cm6.2\text{ cm}6.2 cm.
Use the equation: Rf=distance travelled by the substancedistance travelled by the solventR_f = \frac{\text{distance travelled by the substance}}{\text{distance travelled by the solvent}}Rf=distance travelled by the solventdistance travelled by the substance
Give your answer to 2 significant figures.
A historian claims that the manuscript was written in the 1400s.
Is the historian correct? Explain your answer.