Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 9: Problem 71

Criticize or comment on each of the following statements. (a) Vapor pressure remains constant regardless of volume. (b) The only forces that affect boiling point are dispersion forces. (c) The strength of the covalent bonds within a molecule has no effect on the melting point of the molecular substance. (d) A compound at its critical temperature is always a gas regardless of pressure.

Short Answer

Expert verified
Answer: Vapor pressure remains constant regardless of volume.

Step by step solution

01

(a) Vapor pressure remains constant regardless of volume.

This statement is accurate. Vapor pressure is the pressure exerted by the vapor in equilibrium with its condensed phase (liquid or solid) at a given temperature. It is an intrinsic property of a substance and does not depend on the volume of the container. The vapor pressure depends solely on the temperature and the nature of the substance, but not on the volume.
02

(b) The only forces that affect boiling point are dispersion forces.

This statement is not accurate. Boiling point is affected by various intermolecular forces, including dispersion or London forces, hydrogen bonding, and dipole-dipole interactions. Stronger intermolecular forces result in a higher boiling point as more energy is required to break these forces and convert a liquid into a gas. While dispersion forces are present in all molecules, they are not the only forces that impact boiling point.
03

(c) The strength of the covalent bonds within a molecule has no effect on the melting point of the molecular substance.

This statement is generally accurate. The melting point of a molecular substance is mainly determined by the strength of intermolecular forces, not the strength of covalent bonds within a molecule. Strong covalent bonds indicate stable molecules with high bond dissociation energies, but they do not necessarily correlate with the strength of intermolecular forces that hold the molecules together in the solid phase. However, some covalent substances, like diamond and graphite, have covalent bonds that extend throughout the entire crystal lattice, and in such cases, the melting point can be more influenced by the strength of the covalent bonds.
04

(d) A compound at its critical temperature is always a gas regardless of pressure.

This statement is not accurate. At the critical temperature, a substance can exist in both liquid and gas phases, depending on the pressure applied. Above the critical temperature and pressure, a substance enters a unique state called the supercritical fluid phase, in which it exhibits properties of both liquids and gases. Thus, a compound at its critical temperature is not always in a gaseous state but can also exist as a supercritical fluid when above the critical pressure.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A pure substance \(\mathrm{X}\) has the following properties: \(\mathrm{mp}=90^{\circ} \mathrm{C}\), increasing slightly as pressure increases; normal bp \(=120^{\circ} \mathrm{C}\); liquid vp \(=65 \mathrm{~mm} \mathrm{Hg}\) at \(100^{\circ} \mathrm{C}, 20 \mathrm{~mm} \mathrm{Hg}\) at the triple point. (a) Draw a phase diagram for X. (b) Label solid, liquid, and vapor regions of the diagram. (c) What changes occur if, at a constant pressure of \(100 \mathrm{~mm} \mathrm{Hg}\), the temperature is raised from \(100^{\circ} \mathrm{C}\) to \(150^{\circ} \mathrm{C}\) ?

The data below give the vapor pressure of octane, a major component of gasoline. \(\begin{array}{lllcl}\text { vp }(\mathrm{mm} \mathrm{Hg}) & 10 & 40 & 100 & 400 \\ t\left({ }^{\circ} \mathrm{C}\right) & 19.2 & 45.1 & 65.7 & 104.0\end{array}\) Plot ln vp versus \(1 / T\). Use your graph to estimate the heat of vaporization of octane. \(\left(\ln P=A-\frac{\Delta H_{\mathrm{vap}}}{R}\left(\frac{1}{T}\right)\right.\), where \(A\) is the \(y\) -intercept and \(\Delta H_{\mathrm{vap}}\) is the slope.)

What are the strongest attractive forces that must be overcome to (a) boil silicon hydride \(\mathrm{SiH}_{4} ?\) (b) vaporize calcium chloride? (c) dissolve \(\mathrm{Cl}_{2}\) in carbon tetrachloride, \(\mathrm{CCl}_{4} ?\) (d) melt iodine?

Chloroform, \(\mathrm{CHCl}_{3}\), was once used as an anesthetic. In spy movies it is the liquid put in handkerchiefs to render victims unconscious. Its vapor pressure is \(197 \mathrm{~mm} \mathrm{Hg}\) at \(23^{\circ} \mathrm{C}\) and \(448 \mathrm{~mm} \mathrm{Hg}\) at \(45^{\circ} \mathrm{C}\). Estimate its (a) heat of vaporization. (b) normal boiling point.

The normal boiling point for methyl hydrazine \(\left(\mathrm{CH}_{3} \mathrm{~N}_{2} \mathrm{H}_{3}\right)\) is \(87^{\circ} \mathrm{C}\). It has a vapor pressure of \(37.0 \mathrm{~mm} \mathrm{Hg}\) at \(20^{\circ} \mathrm{C}\). What is the concentration (in \(\mathrm{g} / \mathrm{L}\) ) of methyl hydrazine if it saturates the air at \(25^{\circ} \mathrm{C}\) ?
See all solutions

Recommended explanations on Chemistry Textbooks

The Earths Atmosphere

Read Explanation

Chemistry Branches

Read Explanation

Making Measurements

Read Explanation

Nuclear Chemistry

Read Explanation

Physical Chemistry

Read Explanation

Kinetics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free