Elements Of Physical Chemistry
Elements Of Physical Chemistry
7th Edition
ISBN: 9780198796701
Author: ATKINS, P. W. (peter William), De Paula, Julio
Publisher: Oxford University Press
Question
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Chapter 2, Problem 2.5P

(a)

Interpretation Introduction

Interpretation:

The total contribution to the molar internal energy of gaseous CO2 molecules has to be estimated.

Concept Introduction:

According to equipartition theorem, each translational and rotational degree of freedom contributes 1/2RT to the molar internal energy and each active vibrational degree of freedom contributes RT to the molar internal energy.

(a)

Expert Solution
Check Mark

Explanation of Solution

For all atoms and molecules, there are three translational degrees of freedom. The average molar translational energy is therefore Etrans=3/2RT.

For linear molecules rotate about two axes, perpendicular to the internuclear axis. The average molar rotational energy is therefore Erot=2×1/2RT=RT.

For linear molecules, there are (3N5) vibrational modes.

Consider the molecule CO2.

CO2 with N=3 atoms, the total molar energy is therefore

  E(CO2)=Etrans+Erot+EvibE(CO2)=3RT2+RT+2×(3×35)RTE(CO2)=3RT2+RT+8RTE(CO2)=(212)×8.314JK1mol1×2000KE(CO2)=175kJK1mol1.

(b)

Interpretation Introduction

Interpretation:

The total contribution to the molar internal energy of gaseous C2Br2 molecules has to be estimated.

Concept Introduction:

According to equipartition theorem, each translational and rotational degree of freedom contributes 1/2RT to the molar internal energy and each active vibrational degree of freedom contributes RT to the molar internal energy.

(b)

Expert Solution
Check Mark

Explanation of Solution

For all atoms and molecules, there are three translational degrees of freedom. The average molar translational energy is therefore Etrans=3/2RT.

For linear molecules rotate about two axes, perpendicular to the internuclear axis. The average molar rotational energy is therefore Erot=2×1/2RT=RT.

For linear molecules, there are (3N5) vibrational modes.

Consider the molecule C2Br2.

C2Br2 with N=4 atoms, the total molar energy is therefore

  E(C2Br2)=Etrans+Erot+EvibE(C2Br2)=3RT2+RT+2×(3×45)RTE(C2Br2)=3RT2+RT+14RTE(C2Br2)=(332)×8.314JK1mol1×2000KE(C2Br2)=274kJK1mol1.

(c)

Interpretation Introduction

Interpretation:

The total contribution to the molar internal energy of gaseous NO2 molecules has to be estimated.

Concept Introduction:

According to equipartition theorem, each translational and rotational degree of freedom contributes 1/2RT to the molar internal energy and each active vibrational degree of freedom contributes RT to the molar internal energy.

(c)

Expert Solution
Check Mark

Explanation of Solution

For all atoms and molecules, there are three translational degrees of freedom. The average molar translational energy is therefore Etrans=3/2RT.

For nonlinear molecules rotate about three axes. The average molar rotational energy is therefore Erot=3×1/2RT=3/2RT.

For nonlinear molecules, there are (3N6) vibrational modes.

Consider the molecule NO2.

NO2 with N=3 atoms, the total molar energy is therefore

  E(NO2)=Etrans+Erot+EvibE(NO2)=3RT2+32RT+2×(3×36)RTE(NO2)=3RT2+32RT+6RTE(NO2)=9×8.314JK1mol1×2000KE(NO2)=150kJK1mol1.

(d)

Interpretation Introduction

Interpretation:

The total contribution to the molar internal energy of gaseous C2Br4 molecules has to be estimated.

Concept Introduction:

According to equipartition theorem, each translational and rotational degree of freedom contributes 1/2RT to the molar internal energy and each active vibrational degree of freedom contributes RT to the molar internal energy.

(d)

Expert Solution
Check Mark

Explanation of Solution

For all atoms and molecules, there are three translational degrees of freedom. The average molar translational energy is therefore Etrans=3/2RT.

For nonlinear molecules rotate about three axes. The average molar rotational energy is therefore Erot=3×1/2RT=3/2RT.

For nonlinear molecules, there are (3N6) vibrational modes.

Consider the molecule C2Br4.

C2Br4 with N=6 atoms, the total molar energy is therefore

  E(C2Br4)=Etrans+Erot+EvibE(C2Br4)=3RT2+32RT+2×(3×66)RTE(C2Br4)=3RT2+32RT+24RTE(C2Br4)=27×8.314JK1mol1×2000KE(C2Br4)=449kJK1mol1.

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Chapter 2 Solutions

Elements Of Physical Chemistry

Ch. 2 - Prob. 2D.2STCh. 2 - Prob. 2E.1STCh. 2 - Prob. 2E.2STCh. 2 - Prob. 2E.3STCh. 2 - Prob. 2F.1STCh. 2 - Prob. 2F.2STCh. 2 - Prob. 2F.3STCh. 2 - Prob. 2F.4STCh. 2 - Prob. 2F.5STCh. 2 - Prob. 2F.6STCh. 2 - Prob. 2A.2ECh. 2 - Prob. 2A.3ECh. 2 - Prob. 2A.4ECh. 2 - Prob. 2A.5ECh. 2 - Prob. 2A.6ECh. 2 - Prob. 2A.7ECh. 2 - Prob. 2A.8ECh. 2 - Prob. 2B.1ECh. 2 - Prob. 2B.2ECh. 2 - Prob. 2B.3ECh. 2 - Prob. 2B.4ECh. 2 - Prob. 2B.5ECh. 2 - Prob. 2C.1ECh. 2 - Prob. 2C.2ECh. 2 - Prob. 2D.1ECh. 2 - Prob. 2D.2ECh. 2 - Prob. 2D.3ECh. 2 - Prob. 2D.4ECh. 2 - Prob. 2D.5ECh. 2 - Prob. 2D.6ECh. 2 - Prob. 2E.1ECh. 2 - Prob. 2E.2ECh. 2 - Prob. 2E.3ECh. 2 - Prob. 2E.4ECh. 2 - Prob. 2E.5ECh. 2 - Prob. 2E.6ECh. 2 - Prob. 2E.7ECh. 2 - Prob. 2E.8ECh. 2 - Prob. 2E.9ECh. 2 - Prob. 2F.1ECh. 2 - Prob. 2F.2ECh. 2 - Prob. 2F.3ECh. 2 - Prob. 2F.4ECh. 2 - Prob. 2F.5ECh. 2 - Prob. 2F.6ECh. 2 - Prob. 2F.7ECh. 2 - Prob. 2F.8ECh. 2 - Prob. 2F.9ECh. 2 - Prob. 2F.10ECh. 2 - Prob. 2.1DQCh. 2 - Prob. 2.2DQCh. 2 - Prob. 2.3DQCh. 2 - Prob. 2.4DQCh. 2 - Prob. 2.5DQCh. 2 - Prob. 2.6DQCh. 2 - Prob. 2.7DQCh. 2 - Prob. 2.8DQCh. 2 - Prob. 2.9DQCh. 2 - Prob. 2.10DQCh. 2 - Prob. 2.11DQCh. 2 - Prob. 2.12DQCh. 2 - Prob. 2.13DQCh. 2 - Prob. 2.14DQCh. 2 - Prob. 2.15DQCh. 2 - Prob. 2.16DQCh. 2 - Prob. 2.1PCh. 2 - Prob. 2.2PCh. 2 - Prob. 2.3PCh. 2 - Prob. 2.4PCh. 2 - Prob. 2.5PCh. 2 - Prob. 2.6PCh. 2 - Prob. 2.7PCh. 2 - Prob. 2.8PCh. 2 - Prob. 2.9PCh. 2 - Prob. 2.10PCh. 2 - Prob. 2.12PCh. 2 - Prob. 2.13PCh. 2 - Prob. 2.14PCh. 2 - Prob. 2.15PCh. 2 - Prob. 2.16PCh. 2 - Prob. 2.17PCh. 2 - Prob. 2.18PCh. 2 - Prob. 2.19PCh. 2 - Prob. 2.20PCh. 2 - Prob. 2.21PCh. 2 - Prob. 2.22PCh. 2 - Prob. 2.23PCh. 2 - Prob. 2.25PCh. 2 - Prob. 2.1PRCh. 2 - Prob. 2.2PRCh. 2 - Prob. 2.3PRCh. 2 - Prob. 2.4PRCh. 2 - Prob. 2.5PRCh. 2 - Prob. 2.6PRCh. 2 - Prob. 2.8PRCh. 2 - Prob. 2.9PRCh. 2 - Prob. 2.10PR
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