Solved Worksheet #2 1) Determine the Rf value for the | Chegg.com - Free Printable

Here's a step-by-step solution and explanation for each question on Worksheet #2:

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1) Determine the Rf value for the following sample run:

The Rf value (Retardation factor) is calculated using the formula:

> Rf = distance traveled by the compound / distance traveled by the solvent front

From the image:
- The solvent front reached 10 cm.
- Sample A traveled 10 cm (same as solvent front).
- Sample B traveled 5 cm.

So:

- Rf for Sample A = 10 cm / 10 cm = 1.0
- Rf for Sample B = 5 cm / 10 cm = 0.5

✔ Answer:
- Rf(A) = 1.0
- Rf(B) = 0.5

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2) Is the chromatography paper itself made up of strong or weak IMF?

Chromatography paper is typically made of cellulose, which contains many hydroxyl (-OH) groups. These form strong hydrogen bonds with polar compounds and water.

In paper chromatography, the paper acts as the stationary phase, and it interacts with compounds via intermolecular forces (IMF) — especially hydrogen bonding and dipole-dipole interactions.

Since cellulose can form strong hydrogen bonds, it has strong IMF.

✔ Answer: Strong IMF

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3) Which sample A or B has Strong IMF? How can you tell?

In paper chromatography:
- Compounds that interact strongly with the stationary phase (paper) will move less because they are “held back”.
- Compounds with weak IMF with the paper will travel farther with the mobile phase (solvent).

→ Sample B only traveled 5 cm, meaning it interacted more strongly with the paper and was retained more.

→ Sample A traveled all the way to the solvent front (10 cm), meaning it had very little interaction with the paper.

Therefore, Sample B has stronger IMF with the paper.

✔ Answer: Sample B has strong IMF. It traveled less distance, indicating it was more attracted to (interacted more strongly with) the stationary phase (paper).

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4) Which sample A or B has Weak IMF? How can you tell?

As explained above:
- Sample A traveled the full distance (10 cm), meaning it had minimal interaction with the paper.
- This indicates weak IMF between Sample A and the stationary phase.

✔ Answer: Sample A has weak IMF. It traveled farthest, indicating little attraction to the paper (stationary phase), so it moved easily with the solvent (mobile phase).

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## ✔ Final Summary:

| Question | Answer |
|----------|--------|
| 1) Rf values | A: 1.0, B: 0.5 |
| 2) Paper IMF | Strong IMF (due to cellulose -OH groups) |
| 3) Strong IMF compound | B — traveled less → stronger attraction to paper |
| 4) Weak IMF compound | A — traveled farthest → weaker attraction to paper |

Let me know if you’d like a diagram or further clarification!