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title: "A student investigates the separation of three food dyes, Dye 1, Dye 2, and Dye 3, using paper chromatography. The stationary phase consists of cellulose paper containing numerous polar hydroxyl (\\(-\\text{OH}\\)) groups. The student spots a mixture of the three dyes onto two identical chromatography strips and develops them separately: one in Solvent 1 (pure hexane, a nonpolar solvent) and the other in Solvent 2 (a mixture of ethanol and water, a polar solvent). The retention factor (\\(R_f\\)) values for each dye in both solvents are shown in the table below.  | Dye | \\(R_f\\) in Solvent 1 (Hexane) | \\(R_f\\) in Solvent 2 (Ethanol-Water) | | :— | :— | :— | | Dye 1 | \\(0.12\\) | \\(0.85\\) | | Dye 2 | \\(0.45\\) | \\(0.68\\) | | Dye 3 | \\(0.88\\) | \\(0.22\\) |  Based on the data, which of the following correctly ranks the dyes in order of greatest to least affinity for the stationary phase, and provides the best explanation for the change in the \\(R_f\\) value of Dye 1 when changing from Solvent 1 to Solvent 2?"
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url: "https://nerd-notes.com/ubq/123666/"
date_modified: "2026-09-28T12:01:56+00:00"
---

# A student investigates the separation of three food dyes, Dye 1, Dye 2, and Dye 3, using paper chromatography. The stationary phase consists of cellulose paper containing numerous polar hydroxyl (\(-\text{OH}\)) groups. The student spots a mixture of the three dyes onto two identical chromatography strips and develops them separately: one in Solvent 1 (pure hexane, a nonpolar solvent) and the other in Solvent 2 (a mixture of ethanol and water, a polar solvent). The retention factor (\(R_f\)) values for each dye in both solvents are shown in the table below.

| Dye | \(R_f\) in Solvent 1 (Hexane) | \(R_f\) in Solvent 2 (Ethanol-Water) |
| :— | :— | :— |
| Dye 1 | \(0.12\) | \(0.85\) |
| Dye 2 | \(0.45\) | \(0.68\) |
| Dye 3 | \(0.88\) | \(0.22\) |

Based on the data, which of the following correctly ranks the dyes in order of greatest to least affinity for the stationary phase, and provides the best explanation for the change in the \(R_f\) value of Dye 1 when changing from Solvent 1 to Solvent 2?

A student investigates the separation of three food dyes, Dye 1, Dye 2, and Dye 3, using paper chromatography. The stationary phase consists of cellulose paper containing numerous polar hydroxyl (\(-\text{OH}\)) groups. The student spots a mixture of the three dyes onto two identical chromatography strips and develops them separately: one in Solvent 1 (pure hexane, a nonpolar solvent) and the other in Solvent 2 (a mixture of ethanol and water, a polar solvent). The retention factor (\(R_f\)) values for each dye in both solvents are shown in the table below.

| Dye | \(R_f\) in Solvent 1 (Hexane) | \(R_f\) in Solvent 2 (Ethanol-Water) |
| :--- | :--- | :--- |
| Dye 1 | \(0.12\) | \(0.85\) |
| Dye 2 | \(0.45\) | \(0.68\) |
| Dye 3 | \(0.88\) | \(0.22\) |

Based on the data, which of the following correctly ranks the dyes in order of greatest to least affinity for the stationary phase, and provides the best explanation for the change in the \(R_f\) value of Dye 1 when changing from Solvent 1 to Solvent 2?

- **A.** Ranking: \(\text{Dye 3} > \text{Dye 2} > \text{Dye 1}\) Explanation: The \(R_f\) value of Dye 1 increases because the polar molecules in Solvent 2 break the covalent bonds holding the cellulose stationary phase together.
- **B.** Ranking: \(\text{Dye 3} > \text{Dye 2} > \text{Dye 1}\) Explanation: The \(R_f\) value of Dye 1 increases because Dye 1 forms stronger intermolecular attractions with the polar molecules in Solvent 2 than with the nonpolar molecules in Solvent 1.
- **C.** Ranking: \(\text{Dye 1} > \text{Dye 2} > \text{Dye 3}\) Explanation: The \(R_f\) value of Dye 1 increases because Dye 1 forms stronger intermolecular attractions with the polar molecules in Solvent 2 than with the nonpolar molecules in Solvent 1.
- **D.** Ranking: \(\text{Dye 1} > \text{Dye 2} > \text{Dye 3}\) Explanation: The \(R_f\) value of Dye 1 increases because the larger molar mass of ethanol compared to hexane creates stronger London dispersion forces that push the dye up the paper.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123666/*