---
title: "A student conducts a laboratory investigation to separate a \\(50.0 \\text{ mL}\\) equimolar mixture of ethanol (\\(\\text{CH}_3\\text{CH}_2\\text{OH}\\), normal boiling point \\(78^\\circ\\text{C}\\)) and 1-propanol (\\(\\text{CH}_3\\text{CH}_2\\text{CH}_2\\text{OH}\\), normal boiling point \\(97^\\circ\\text{C}\\)) using fractional distillation. In Trial 1, the vertical fractionating column is packed with inert glass beads. In Trial 2, the student inadvertently omits the glass beads, leaving the vertical column empty, while keeping all other apparatus components and heating parameters identical. The student collects the initial \\(5.0 \\text{ mL}\\) of distillate for both trials and records the data shown in the table below.  | Trial | Fractionating column packing | Distillation head temperature (\\(^\\circ\\text{C}\\)) | Mole fraction of \\(\\text{CH}_3\\text{CH}_2\\text{OH}\\) in initial \\(5.0 \\text{ mL}\\) distillate | | :—: | :—: | :—: | :—: | | 1 | Packed with glass beads | \\(78\\) | \\(0.96\\) | | 2 | Empty (no packing) | \\(85\\) | \\(0.68\\) |  Which of the following best explains why the initial distillate collected in Trial 2 has a substantially lower mole fraction of \\(\\text{CH}_3\\text{CH}_2\\text{OH}\\) than that collected in Trial 1?"
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url: "https://nerd-notes.com/ubq/123665/"
date_modified: "2026-09-28T12:01:56+00:00"
---

# A student conducts a laboratory investigation to separate a \(50.0 \text{ mL}\) equimolar mixture of ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\), normal boiling point \(78^\circ\text{C}\)) and 1-propanol (\(\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}\), normal boiling point \(97^\circ\text{C}\)) using fractional distillation. In Trial 1, the vertical fractionating column is packed with inert glass beads. In Trial 2, the student inadvertently omits the glass beads, leaving the vertical column empty, while keeping all other apparatus components and heating parameters identical. The student collects the initial \(5.0 \text{ mL}\) of distillate for both trials and records the data shown in the table below.

| Trial | Fractionating column packing | Distillation head temperature (\(^\circ\text{C}\)) | Mole fraction of \(\text{CH}_3\text{CH}_2\text{OH}\) in initial \(5.0 \text{ mL}\) distillate |
| :—: | :—: | :—: | :—: |
| 1 | Packed with glass beads | \(78\) | \(0.96\) |
| 2 | Empty (no packing) | \(85\) | \(0.68\) |

Which of the following best explains why the initial distillate collected in Trial 2 has a substantially lower mole fraction of \(\text{CH}_3\text{CH}_2\text{OH}\) than that collected in Trial 1?

A student conducts a laboratory investigation to separate a \(50.0 \text{ mL}\) equimolar mixture of ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\), normal boiling point \(78^\circ\text{C}\)) and 1-propanol (\(\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}\), normal boiling point \(97^\circ\text{C}\)) using fractional distillation. In Trial 1, the vertical fractionating column is packed with inert glass beads. In Trial 2, the student inadvertently omits the glass beads, leaving the vertical column empty, while keeping all other apparatus components and heating parameters identical. The student collects the initial \(5.0 \text{ mL}\) of distillate for both trials and records the data shown in the table below.

| Trial | Fractionating column packing | Distillation head temperature (\(^\circ\text{C}\)) | Mole fraction of \(\text{CH}_3\text{CH}_2\text{OH}\) in initial \(5.0 \text{ mL}\) distillate |
| :---: | :---: | :---: | :---: |
| 1 | Packed with glass beads | \(78\) | \(0.96\) |
| 2 | Empty (no packing) | \(85\) | \(0.68\) |

Which of the following best explains why the initial distillate collected in Trial 2 has a substantially lower mole fraction of \(\text{CH}_3\text{CH}_2\text{OH}\) than that collected in Trial 1?

- **A.** The lack of packing material allows vapor to reach the condenser too rapidly, which prevents the cooling water in the condenser jacket from selectively liquefying the higher-boiling component.
- **B.** The lack of packing material alters the intermolecular attractions between the alcohol molecules and the column wall, significantly lowering the normal boiling points of both liquids.
- **C.** The lack of packing material reduces the internal surface area required for repeated vaporization-condensation cycles, preventing the ascending vapor from becoming progressively enriched in the more volatile component.
- **D.** The lack of packing material allows radiant thermal energy from the heating mantle to reach the thermometer, which prevents complete vaporization of the liquid mixture in the flask.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123665/*