In paper chromatography, what is a likely consequence if a student uses a pen to mark the baseline instead of a pencil?

• A. The ink from the pen may dissolve in the solvent and interfere with the separation of the sample.
• B. There will be no effect, as the pen ink is insoluble in all solvents used in chromatography.
• C. The pen mark will react with the sample, causing the paper to tear.
• D. The baseline will be more visible, improving the accuracy of the experiment.

Answer: (A)

Verified step by step guidance

1. Understand the purpose of marking the baseline in paper chromatography: it serves as the starting point where the sample spots are applied.
2. Recognize that the baseline must be marked with a substance that does not dissolve in the solvent used during chromatography, to avoid interference.
3. Consider the difference between pen ink and pencil marks: pencil marks are made of graphite, which is generally insoluble in common chromatography solvents, while pen ink often contains dyes or pigments that can dissolve.
4. Predict what happens if pen ink dissolves: the ink can move with the solvent front, mixing with the sample components and causing inaccurate or confusing results.
5. Conclude that using a pen to mark the baseline can lead to the ink dissolving in the solvent and interfering with the separation process, which is why pencil is preferred.