Selected ATcT [1, 2] enthalpy of formation based on version 1.156 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.148 to include species relevant to a recent study of the oxidation of ethylene [4] as well as new measurements that led to refining the thermochemistry of CF and SiF and their cations [5].

Dibromine

Formula: Br2 (g)

CAS RN: 7726-95-6

ATcT ID: 7726-95-6*0

SMILES: BrBr

InChI: InChI=1S/Br2/c1-2

InChIKey: GDTBXPJZTBHREO-UHFFFAOYSA-N

Hills Formula: Br2

2D Image:

Aliases: Br2; Dibromine; Bromine molecule; Bromine; Molecular bromine; Diatomic bromine; UN 1744

Relative Molecular Mass: 159.8080 ± 0.0020

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
45.70	30.90	± 0.11	kJ/mol

3D Image of Br2 (g)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of Br2 (g)

The 1 contributors listed below account for 93.1% of the provenance of Δ_fH° of Br2 (g).

Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.

Contribution (%)	TN ID	Reaction	Measured Quantity	Reference
93.1	1099.2	Br2 (cr,l) → Br2 (g)	Δ_rH°(298.15 K) = 7.386 ± 0.027 kcal/mol	Hildenbrand 1958

Top 10 species with enthalpies of formation correlated to the Δ_fH° of Br2 (g)

Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances.
The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.

Correlation Coefficent (%)	Species Name	Formula	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
100.0	Bromine atom	Br (g)	117.925	111.863	± 0.055	kJ/mol	79.90400 ± 0.00100	10097-32-2*0
100.0	Bromine atom	Br (g, 2P3/2)	117.925	111.863	± 0.055	kJ/mol	79.90400 ± 0.00100	10097-32-2*1
100.0	Bromine atom	Br (g, 2P1/2)	162.009	155.947	± 0.055	kJ/mol	79.90400 ± 0.00100	10097-32-2*2
100.0	Bromide	Br- (g)	-206.612	-212.674	± 0.055	kJ/mol	79.90455 ± 0.00100	24959-67-9*0
99.4	Bromanylium	Br+ (g)	1257.786	1251.723	± 0.056	kJ/mol	79.90345 ± 0.00100	22541-56-6*0
93.5	Bromochlorane	BrCl (g)	21.891	14.447	± 0.059	kJ/mol	115.3567 ± 0.0013	13863-41-7*0
83.1	Iodine monobromide	IBr (g)	49.727	40.780	± 0.066	kJ/mol	206.8085 ± 0.0010	7789-33-5*0
48.6	Diatomic bromine cation	[Br2]+ (g)	1060.34	1045.39	± 0.23	kJ/mol	159.8075 ± 0.0020	12595-71-0*0
34.0	Hydrogen bromide	HBr (g)	-27.51	-35.36	± 0.12	kJ/mol	80.9119 ± 0.0010	10035-10-6*0
34.0	Bromoniumyl	[HBr]+ (g)	1098.16	1090.31	± 0.12	kJ/mol	80.9114 ± 0.0010	12258-64-9*0

Most Influential reactions involving Br2 (g)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence Coefficient	TN ID	Reaction	Measured Quantity	Reference
0.996	7427.1	Br2 (g) + CH2F2 (g) → HBr (g) + CHF2Br (g)	Δ_rH°(298.15 K) = -9.54 ± 0.07 kcal/mol	Okafo 1974, as quoted by Cox 1970
0.931	1099.2	Br2 (cr,l) → Br2 (g)	Δ_rH°(298.15 K) = 7.386 ± 0.027 kcal/mol	Hildenbrand 1958
0.897	6705.3	CO (g) + Br2 (g) → CBr2O (g)	Δ_rG°(444 K) = 6.169 ± 0.088 kcal/mol	Dunning 1972, 3rd Law
0.821	1100.13	Br2 (g) → 2 Br (g)	Δ_rH°(0 K) = 15895.537 ± 0.020 cm-1	Gerstenkorn 1989, Br 79.90
0.804	6278.1	Br2 (g) + CHCl3 (g) → HBr (g) + CCl3Br (g)	Δ_rH°(298.15 K) = -1.41 ± 0.10 kcal/mol	Mendenhall 1973, as quoted by Pedley 1986
0.789	6489.2	CF3CF3 (g) + Br2 (g) → 2 CF3Br (g)	Δ_rG°(670.8 K) = -1.58 ± 0.62 kJ/mol	Coomber 1967a, 3rd Law
0.762	7457.1	CH2CH2 (g) + Br2 (g) → CH2BrCH2Br (g)	Δ_rH°(355 K) = -29.058 ± 0.300 kcal/mol	Conn 1938
0.706	1213.6	2 BrCl (g) → Br2 (g) + Cl2 (g)	Δ_rG°(295.15 K) = 5.419 ± 0.049 kJ/mol	Tellinghuisen 2003, 3rd Law
0.586	1114.1	Br- (g) + Br2 (g) → [Br2]- (g) + Br (g)	Δ_rH°(0 K) = 0.84 ± 0.03 eV	Chupka 1971b
0.527	6283.1	CHBr3 (g) + Br2 (g) → CBr4 (g) + HBr (g)	Δ_rG°(588.3 K) = 3.27 ± 1.00 kJ/mol	King 1971, 3rd Law
0.458	1102.1	Br2 (g) → [Br2]+ (g)	Δ_rH°(0 K) = 10.518 ± 0.003 eV	Yencha 1995
0.289	1197.4	[Br3]- (g) → Br- (g) + Br2 (g)	Δ_rH°(298.15 K) = 30.6 ± 0.8 kcal/mol	Thanthiriwatte 2014, est unc
0.246	1283.1	I- (g) + Br2 (g) → [Br2]- (g) + I (g)	Δ_rH°(0 K) = 0.59 ± 0.03 (×1.542) eV	Chupka 1971b
0.202	1196.1	Br3 (g) → Br2 (g) + Br (g)	Δ_rH°(0 K) = 13 ± 7 kJ/mol	Kawasaki 1989
0.184	5928.1	CCl3 (g) + Br2 (g) → CCl3Br (g) + Br (g)	Δ_rG°(437 K) = -3.5 ± 0.5 kcal/mol	Hudgens 1991, 3rd Law
0.165	1102.2	Br2 (g) → [Br2]+ (g)	Δ_rH°(0 K) = 10.515 ± 0.005 eV	van Lonkhuyzen 1984
0.165	1102.7	Br2 (g) → [Br2]+ (g)	Δ_rH°(0 K) = 10.516 ± 0.005 eV	Ruscic 1994
0.138	6277.1	Br2 (g) + CCl4 (g) → BrCl (g) + CCl3Br (g)	Δ_rH°(298.15 K) = 8.84 ± 0.30 kcal/mol	Mendenhall 1973, as quoted by Pedley 1986
0.117	1211.9	2 BrCl (g) → Br2 (g) + Cl2 (g)	Δ_rG°(301.15 K) = 5.54 ± 0.12 kJ/mol	Vesper 1934, 3rd Law, est unc
0.097	6255.1	CF3Cl (g) + Br2 (g) → CF3Br (g) + BrCl (g)	Δ_rH°(298.15 K) = 10.49 ± 0.40 (×1.114) kcal/mol	Coomber 1967b, as quoted by Cox 1970

References

1		B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner, Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited. J. Phys. Chem. A 108, 9979-9997 (2004) [DOI: 10.1021/jp047912y]
2		B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner, Active Thermochemical Tables: Thermochemistry for the 21^st Century. J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3		B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.156 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		N. A. Seifert, B. Ruscic, R. Sivaramakrishnan, and K. Prozument, The C2H4O Isomers in the Oxidation of Ethylene J. Mol. Spectrosc. 398, 111847/1-8 (2023) [DOI: 10.1016/j.jms.2023.111847]
5		U. Jacovella, B. Ruscic, N. L. Chen, H.-L. Le, S. Boyé-Péronne, S. Hartweg, M. Roy-Chowdhury, G. A. Garcia, J.-C. Loison, and B. Gans, Refining Thermochemical Properties of CF, SiF, and Their Cations by Combining Photoelectron Spectroscopy, Quantum Chemical Calculations, and the Active Thermochemical Tables Approach Phys. Chem. Chem. Phys. 25, 30838-30847 (2023) [DOI: 10.1039/D3CP04244H]
6		B. Ruscic, Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables. Int. J. Quantum Chem. 114, 1097-1101 (2014) [DOI: 10.1002/qua.24605]
7		B. Ruscic and D. H. Bross, Thermochemistry Computer Aided Chem. Eng. 45, 3-114 (2019) [DOI: 10.1016/B978-0-444-64087-1.00001-2]

Formula

The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.

Uncertainties

The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [6] and Ruscic and Bross[7]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000₅ kJ/mol.

Website Functionality Credits

The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.

Acknowledgement

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.