Boron
- Formula: B2
- Molecular weight: 21.622
- IUPAC Standard InChI: InChI=1S/B2/c1-2
- IUPAC Standard InChIKey: ZOCHARZZJNPSEU-UHFFFAOYSA-N
- CAS Registry Number: 14452-61-0
- Chemical structure:
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Gas phase thermochemistry data
Go To: Top, Constants of diatomic molecules, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°gas | 198.30 | kcal/mol | Review | Chase, 1998 | Data last reviewed in March, 1979 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 48.296 | cal/mol*K | Review | Chase, 1998 | Data last reviewed in March, 1979 |
Gas Phase Heat Capacity (Shomate Equation)
Cp° = A + B*t + C*t2 + D*t3 +
E/t2
H° − H°298.15= A*t + B*t2/2 +
C*t3/3 + D*t4/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t2/2 + D*t3/3 −
E/(2*t2) + G
Cp = heat capacity (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/mol*K)
t = temperature (K) / 1000.
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| Temperature (K) | 298. to 800. | 800. to 6000. |
|---|---|---|
| A | -1.330230 | 10.35670 |
| B | 35.97770 | -0.864833 |
| C | -40.79039 | 0.226905 |
| D | 15.81880 | -0.016130 |
| E | 0.121037 | -0.084268 |
| F | 197.8330 | 194.6400 |
| G | 38.31401 | 59.81580 |
| H | 198.3000 | 198.3000 |
| Reference | Chase, 1998 | Chase, 1998 |
| Comment | Data last reviewed in March, 1979 | Data last reviewed in March, 1979 |
Constants of diatomic molecules
Go To: Top, Gas phase thermochemistry data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: Klaus P. Huber and Gerhard H. Herzberg
Data collected through September, 1976
| Symbol | Meaning |
|---|---|
| State | electronic state and / or symmetry symbol |
| Te | minimum electronic energy (cm-1) |
| ωe | vibrational constant – first term (cm-1) |
| ωexe | vibrational constant – second term (cm-1) |
| ωeye | vibrational constant – third term (cm-1) |
| Be | rotational constant in equilibrium position (cm-1) |
| αe | rotational constant – first term (cm-1) |
| γe | rotation-vibration interaction constant (cm-1) |
| De | centrifugal distortion constant (cm-1) |
| βe | rotational constant – first term, centrifugal force (cm-1) |
| re | internuclear distance (Å) |
| Trans. | observed transition(s) corresponding to electronic state |
| ν00 | position of 0-0 band (units noted in table) |
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A 3Σu- | 30573.4 | 937.4 Z | 2.6 | 1.160 | 0.011 | 1.625 | A ↔ X R | 30518.10 Z | ||||
| ↳missing citation; Nicholls, Fraser, et al., 1959; Graham and Weltner, 1976 | ||||||||||||
| X 3Σg- | 0 | 1051.3 Z | 9.35 | 1.212 | 0.014 | 1.590 | ||||||
Notes
| 1 | Thermochemical value (mass-spectrom.); from Verhaegen and Drowart, 1962, but using the higher value from Stull and Prophet, 1971 for the heat of sublimation of boron. |
| 2 | Experimental evidence Graham and Weltner, 1976 supports a 3Σ ground state; theoretical calculations Bender and Davidson, 1967 predict a 5Σu- state at approximately 1100 cm-1 below the lowest state of 3Σg- symmetry. |
References
Go To: Top, Gas phase thermochemistry data, Constants of diatomic molecules, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Chase, 1998
Chase, M.W., Jr.,
NIST-JANAF Themochemical Tables, Fourth Edition,
J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]
Nicholls, Fraser, et al., 1959
Nicholls, R.W.; Fraser, P.A.; Jarmain, W.R.,
Transition probability parameters of molecular spectra arising from combustion processes,
Combust. Flame, 1959, 3, 13. [all data]
Graham and Weltner, 1976
Graham; Weltner,
Private communication cited in Huber and Herzberg, 1979, 1976, 65. [all data]
Verhaegen and Drowart, 1962
Verhaegen, G.; Drowart, J.,
Mass spectrometric determination of the heat of sublimation of boron and of the dissociation energy of B2,
J. Chem. Phys., 1962, 37, 1367. [all data]
Stull and Prophet, 1971
Stull, D.R.; Prophet, H.,
JANAF Thermochemical Tables. Second Edition, Office of SRD (NSRDS-NBS 37), Washington, D.C., 1971, 0. [all data]
Bender and Davidson, 1967
Bender, C.F.; Davidson, E.R.,
Electronic structure of the B2 molecule,
J. Chem. Phys., 1967, 46, 3313. [all data]
Huber and Herzberg, 1979
Huber, K.P.; Herzberg, G.,
Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules, Van Nostrand Reinhold Company, New York, 1979, 716. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Constants of diatomic molecules, References
- Symbols used in this document:
S°gas,1 bar Entropy of gas at standard conditions (1 bar) ΔfH°gas Enthalpy of formation of gas at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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