Set up paper chromatography and interpret a chromatogram.
| English | Chinese |
|---|---|
| chromatography | 色谱法 |
| baseline | 基线 |
| solvent front | 溶剂前沿 |
| chromatogram | 色谱图 |
Try each question before opening its hint or answer. Use paper for calculations and diagrams.
Why should the initial ink spot sit above the solvent level?
The solvent must carry the sample up the paper from the baseline.
If the spot is submerged, the sample may dissolve directly into the solvent reservoir instead of travelling up the paper.
Why should a chromatography baseline be drawn in pencil rather than ink?
Consider whether the marking material can dissolve in the solvent.
Ink may dissolve and separate into extra spots. The graphite in a pencil line does not dissolve in the chromatography solvent.
An unknown gives spots at 2 cm and 5 cm. Reference P gives one spot at 2 cm in the same run. What can you conclude?
Separate evidence of a mixture from evidence for a possible identity.
The unknown is a mixture because it separates into two spots. The matching spot suggests P may be present; one matching position alone does not prove identity.
Use Lesson 4 in your worksheet for written practice. Your teacher will discuss those answers in class.