---
title: "A student studies the recovery of hexane and heptane from an ideal liquid mixture. At \\(40^{\\circ}\\text{C}\\), the pure-component vapor pressures are \\(P_{\\text{C}_6\\text{H}_{14}}^{\\circ}=36\\ \\text{kPa}\\) and \\(P_{\\text{C}_7\\text{H}_{16}}^{\\circ}=12\\ \\text{kPa}\\). The particulate diagram represents the composition of the liquid phase at equilibrium. For each component \\(i\\), the partial pressure and vapor-phase mole fraction are related to the liquid-phase mole fraction by  \\[ P_i=x_iP_i^{\\circ}\\qquad\\text{and}\\qquad y_i=\\dfrac{P_i}{P_{\\text{total}}} \\]  The total number of symbols in each answer diagram is arbitrary; only the ratio of the two types of symbols represents vapor composition. Which diagram best represents the mole fractions of hexane and heptane in the equilibrium vapor phase?"
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url: "https://nerd-notes.com/ubq/120126/"
date_modified: "2026-08-21T08:42:18+00:00"
---

# A student studies the recovery of hexane and heptane from an ideal liquid mixture. At \(40^{\circ}\text{C}\), the pure-component vapor pressures are \(P_{\text{C}_6\text{H}_{14}}^{\circ}=36\ \text{kPa}\) and \(P_{\text{C}_7\text{H}_{16}}^{\circ}=12\ \text{kPa}\). The particulate diagram represents the composition of the liquid phase at equilibrium. For each component \(i\), the partial pressure and vapor-phase mole fraction are related to the liquid-phase mole fraction by

\[
P_i=x_iP_i^{\circ}\qquad\text{and}\qquad y_i=\dfrac{P_i}{P_{\text{total}}}
\]

The total number of symbols in each answer diagram is arbitrary; only the ratio of the two types of symbols represents vapor composition. Which diagram best represents the mole fractions of hexane and heptane in the equilibrium vapor phase?

A student studies the recovery of hexane and heptane from an ideal liquid mixture. At \(40^{\circ}\text{C}\), the pure-component vapor pressures are \(P_{\text{C}_6\text{H}_{14}}^{\circ}=36\ \text{kPa}\) and \(P_{\text{C}_7\text{H}_{16}}^{\circ}=12\ \text{kPa}\). The particulate diagram represents the composition of the liquid phase at equilibrium. For each component \(i\), the partial pressure and vapor-phase mole fraction are related to the liquid-phase mole fraction by

\[
P_i=x_iP_i^{\circ}\qquad\text{and}\qquad y_i=\dfrac{P_i}{P_{\text{total}}}
\]

The total number of symbols in each answer diagram is arbitrary; only the ratio of the two types of symbols represents vapor composition. Which diagram best represents the mole fractions of hexane and heptane in the equilibrium vapor phase?

![A legend at the upper left maps an open white circle to one \(\text{C}_6\text{H}_{14}\) molecule and a solid black circle to one \(\text{C}_7\text{H}_{16}\) molecule. Below the legend, draw a wide rectangular region representing a sample from the liquid phase, with a horizontal surface line across its top. Inside the liquid region place exactly \(8\) separated particles in \(2\) staggered horizontal rows of \(4\). In the upper row, from left to right, place an open circle followed by \(3\) solid circles. In the lower row, place \(2\) solid circles, then an open circle, then a solid circle. Make all circles the same diameter and distribute them uniformly without bonds or overlaps. Use a white background and strictly grayscale styling. No other particles, labels, text, arrows, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787301737-jXw5pN.jpg)

- **A.** Diagram A
- **B.** Diagram B
- **C.** Diagram C
- **D.** Diagram D

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120126/*