/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 90 As the temperature of a diatomic... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

As the temperature of a diatomic gas increases, we expect its specific heat to A. remain the same B. increase C. decrease

Short Answer

Expert verified
B. increase

Step by step solution

01

Understanding Diatomic Gas

Diatomic gases are gases composed of molecules with two atoms. Common examples include oxygen (Oâ‚‚) and nitrogen (Nâ‚‚). These molecules have more degrees of freedom compared to monatomic gases, which affects their specific heat.
02

Degree of Freedom

For a diatomic gas, the degrees of freedom include translational, rotational, and vibrational modes. At room temperature, the translational and rotational modes are primarily active, contributing to the specific heat.
03

Temperature Impact on Degrees of Freedom

As the temperature increases, vibrational modes become more active. This is due to the fact that higher temperatures provide sufficient energy to excite vibrational motion in addition to translational and rotational motion.
04

Specific Heat and Degrees of Freedom

The specific heat of a gas is directly related to its degrees of freedom. When vibrational modes are excited at higher temperatures in diatomic gases, the degrees of freedom increase, leading to an increase in specific heat.
05

Conclusion on Specific Heat Behavior

Given that more energy states (degrees of freedom) are accessible at higher temperatures for diatomic gases, we can conclude that the specific heat of a diatomic gas increases with temperature.

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.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Diatomic Gases
Diatomic gases are fascinating due to the simplicity yet complexity of their molecules. Each molecule is made up of two atoms, as the name 'diatomic' suggests. Common examples you might be familiar with include oxygen (Oâ‚‚) and nitrogen (Nâ‚‚), which make up a large portion of the Earth's atmosphere.

The unique aspect of diatomic gases is their behavior compared to monatomic gases (gases composed of single atoms, like helium). Because they consist of two atoms, diatomic gases have additional modes of motion, which affect their energy states and thus, their thermal properties. This additional complexity plays a significant role in how we understand the specific heat of these gases.
Degrees of Freedom
Degrees of freedom refer to the different ways molecules can store energy. For diatomic gases, these include several kinds of motion.
  • Translational Motion: Moving in three-dimensional space
  • Rotational Motion: Spinning around their center of mass
  • Vibrational Motion: Atoms within the molecule oscillating back and forth
At standard conditions, diatomic gases can freely translate and rotate, keeping their energy primarily in these modes. As a result, the specific heat is calculated based on these accessible degrees of freedom.
The introduction of vibrational motion at higher temperatures represents an increase in these degrees of freedom, which significantly impacts the thermal properties of the gas.
Temperature Effects
Temperature has a profound influence on diatomic gases and their behavior. At room temperature, only translational and rotational motions are sufficiently excited to contribute to the energy.
As the temperature increases, molecular energy levels expand, and vibrational motion becomes active. This occurs because higher temperatures provide the gas molecules with additional energy.
The impact of these new vibrational modes results in changes to the thermodynamic properties, such as an increase in specific heat. Understanding how temperature affects these degrees of freedom is key to predicting the behavior of diatomic gases under various thermal conditions.
Vibrational Modes
Vibrational modes refer to the oscillatory motion of atoms within a molecule. In diatomic molecules, this is analogous to two masses connected by a spring. These modes are generally not excited at lower temperatures due to insufficient energy.

However, as the temperature rises, the energy levels occupied by these modes also increase. This activation of vibrational modes adds to the degrees of freedom, thus raising the specific heat capacity of the gas.
  • The more degrees of freedom a molecule has, the more ways it can store heat energy.
  • Higher temperatures facilitate the activation of these additional modes.
The inclusion of vibrational modes at higher temperatures is an essential factor when calculating the specific heat capacity of diatomic gases, making it critical in studies related to thermodynamics and heat capacity.

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

\(\bullet\) Five moles of an ideal monatomic gas with an initial temperature of \(127^{\circ} \mathrm{C}\) expand and, in the process, absorb 1200 \(\mathrm{J}\) of heat and do 2100 \(\mathrm{J}\) of work. What is the final temperature of the gas?

\(\bullet$$\cdot\) An ideal gas at 4.00 atm and 350 \(\mathrm{K}\) is permitted to expand adiabatically to 1.50 times its initial volume. Find the final pressure and temperature if the gas is (a) monatomic with \(C_{p} / C_{V}=\frac{5}{3},\) (b) diatomic with \(C_{p} / C_{V}=\frac{7}{5} .\)

\(\bullet\) You are keeping 1.75 moles of an ideal gas in a container surrounded by a large ice-water bath that maintains the temperature of the gas at \(0.00^{\circ} \mathrm{C}\) (a) How many joules of work would have to be done on this gas to compress its volume from 4.20 \(\mathrm{L}\) to 1.35 \(\mathrm{L} ?\) (b) How much heat came into (or out of) the gas during this process? Was it into or out of?

For an ideal gas with 9 degrees of freedom, the molar heat capacity at constant volume \((\mathrm{J} /(\mathrm{mol} \cdot \mathrm{K}))\) would be $$\begin{array}{l}{\text { A. } \frac{3}{2} R T} \\ {\text { B. } \frac{3}{2} n R} \\ {\text { C. } \frac{9}{2} n R} \\ {\text { D. } \frac{9}{2} R} \\\ {\text { E. } \frac{11}{2} R}\end{array}$$

\(\bullet$$\bullet$$\bullet\) A hot-air balloon stays aloft because hot air at atmospheric pressure is less dense than cooler air at the same pressure. (The calculation of the buoyant force is discussed in Chapter \(13 .\) ) If the volume of the balloon is 500.0 \(\mathrm{m}^{3}\) and the surrounding air is at \(15.0^{\circ} \mathrm{C},\) what must the temperature of the air in the balloon be for it to lift a total load of 290 \(\mathrm{kg}\) (in addition to the mass of the hot air)? The density of air at \(15.0^{\circ} \mathrm{C}\) and atmospheric pressure is 1.23 \(\mathrm{kg} / \mathrm{m}^{3}.\) BIO Temperature and degrees of freedom. The internal energy of an ideal monatomic gas is simply the kinetic energy associated with the translational motion of its atoms as they move randomly in each of the three independent spatial dimensions. However, for a diatomic ideal gas we must also take into account the kinetic and potential energies associated with molecular vibration, and the kinetic energy associated with molecular rotation. Roughly speaking, each independent way that energy can be stored is known as a degree of freedom. Although translational motion can occur at any temperature, rotational and vibrational motions typically cannot occur at lower temperatures- thus, the number of available degrees of freedom can change as the temperature changes. For example, an ideal monatomic gas has three degrees of freedom (one for each of its independent directions of translational motion) at all temperatures. In contrast, diatomic hydrogen \(\left(\mathrm{H}_{2}\right)\) has five degrees of freedom near room temperature \((3\) translational and 2 rotational). However, at higher temperatures, where molecular vibrations can occur, diatomic hydrogen has seven degrees of freedom \((3\) translational, 2 rotational, and 2 vibrational). The equipartition theorem states that equilibrium each degree of freedom contributes \(\frac{1}{2} n R T\) to the internal energy of the gas. For example, the internal energy of a monatomic gas, which has 3 degrees of freedom, would be \(\frac{3}{2} n R T\).

See all solutions

Recommended explanations on Physics Textbooks

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.