Selected ATcT [1, 2] enthalpy of formation based on version 1.176 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.172 to include species related to Criegee intermediates that are involved in several ongoing studies[4].

Acetylene

Formula: HCCH (g)

CAS RN: 74-86-2

ATcT ID: 74-86-2*0

SMILES: C#C

InChI: InChI=1S/C2H2/c1-2/h1-2H

InChIKey: HSFWRNGVRCDJHI-UHFFFAOYSA-N

Hills Formula: C2H2

2D Image:

Aliases: HCCH; Acetylene; Ethyne; Narcylen; Vinylene; CHCH

Relative Molecular Mass: 26.0373 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
228.86	228.30	± 0.12	kJ/mol

3D Image of HCCH (g)

spin ON spin OFF

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

The 20 contributors listed below account only for 26.9% of the provenance of Δ_fH° of HCCH (g).
A total of 733 contributors would be needed to account for 90% of the provenance.

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
2.9	2375.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
2.5	2268.11	CO (g) → C (g) + O (g)	Δ_rH°(0 K) = 1071.92 ± 0.10 kJ/mol	Thorpe 2021
1.8	2286.9	C (graphite) + CO2 (g) → 2 CO (g)	Δ_rG°(1165 K) = -33.545 ± 0.058 kJ/mol	Smith 1946, note COf, 3rd Law
1.6	2596.7	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1626.04 ± 0.56 kJ/mol	Harding 2008
1.3	2595.13	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 388.71 ± 0.15 kcal/mol	Karton 2007a
1.3	2310.7	HCCH (g) → 2 H (g) + C2 (g)	Δ_rH°(0 K) = 244.65 ± 0.15 kcal/mol	Karton 2007a
1.3	125.2	1/2 O2 (g) + H2 (g) → H2O (cr,l)	Δ_rH°(298.15 K) = -285.8261 ± 0.040 kJ/mol	Rossini 1939, Rossini 1931, Rossini 1931b, note H2Oa, Rossini 1930
1.2	2278.2	CO (g) → C+ (g) + O (g)	Δ_rH°(0 K) = 22.3713 ± 0.0015 eV	Ng 2007
1.1	2614.2	CH2CH2 (g) → [HCCH]+ (g) + H2 (g)	Δ_rH°(0 K) = 13.135 ± 0.005 (×1.354) eV	Mahnert 1996
1.1	2614.1	CH2CH2 (g) → [HCCH]+ (g) + H2 (g)	Δ_rH°(0 K) = 13.135 ± 0.005 (×1.354) eV	Malow 1999, est unc
1.1	2228.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
1.0	2596.5	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1626.04 ± 0.70 kJ/mol	Harding 2008, Ferguson 2013
1.0	2596.4	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1626.21 ± 0.70 kJ/mol	Bomble 2006
1.0	2596.11	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1626.15 ± 0.70 kJ/mol	Harding 2007
1.0	2612.6	HCCH (g) + H2 (g) → CH2CH2 (g)	Δ_rH°(0 K) = -167.71 ± 0.70 kJ/mol	Harding 2007
1.0	2529.1	CH2CH2 (g) + 3 O2 (g) → 2 CO2 (g) + 2 H2O (cr,l)	Δ_rH°(298.15 K) = -1411.18 ± 0.30 kJ/mol	Rossini 1937
0.9	2596.6	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1625.72 ± 0.74 kJ/mol	Harding 2008
0.9	2611.11	HCCH (g) + 2 H2 (g) → CH3CH3 (g)	Δ_rH°(0 K) = -71.01 ± 0.20 kcal/mol	Karton 2007
0.9	2596.3	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1625.88 ± 0.75 kJ/mol	Bomble 2006
0.9	2596.1	HCCH (g) → 2 C (g) + 2 H (g)	Δ_rH°(0 K) = 1626.06 ± 0.75 kJ/mol	Tajti 2004, est unc

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HCCH (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	Acetylene cation	[HCCH]+ (g)	1328.88	1328.21	± 0.12	kJ/mol	26.0367 ± 0.0016	25641-79-6*0
78.7	Ethynylium	[CCH]+ (g)	1687.62	1690.95	± 0.15	kJ/mol	25.0288 ± 0.0016	16456-59-0*0
64.5	Ethynyl	CCH (g)	563.73	567.85	± 0.15	kJ/mol	25.0293 ± 0.0016	2122-48-7*0
55.5	Carbon cation	C+ (g)	1797.834	1803.432	± 0.039	kJ/mol	12.01015 ± 0.00080	14067-05-1*0
55.5	Carbon	C (g, triplet)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*1
55.5	Carbon	C (g)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*0
55.5	Carbon	C (g, singlet)	833.312	838.459	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*2
55.5	Carbon	C (g, quintuplet)	1114.944	1120.091	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*3
55.4	Carbon dication	[C]+2 (g)	4150.451	4155.597	± 0.039	kJ/mol	12.00960 ± 0.00080	16092-61-8*0
55.2	Carbon anion	C- (g)	589.605	594.751	± 0.039	kJ/mol	12.01125 ± 0.00080	14337-00-9*0

Most Influential reactions involving HCCH (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
0.980	2598.1	HCCH (g) → [HCCH]+ (g)	Δ_rH°(0 K) = 91953.77 ± 0.06 cm-1	Tang 2006
0.872	2653.5	HCCH (g) → [CCH]+ (g) + H (g)	Δ_rH°(0 K) = 17.3576 ± 0.0010 eV	Jarvis 1999, Weitzel 2001
0.598	7603.1	CHICHI (g, trans) → HCCH (g) + I2 (g)	Δ_rG°(600 K) = 1.26 ± 0.10 kcal/mol	Furuyama 1968
0.598	7602.1	CHICHI (g, cis) → HCCH (g) + I2 (g)	Δ_rG°(600 K) = 0.60 ± 0.10 kcal/mol	Furuyama 1968
0.394	6230.8	HCCH (g) + ClCCCl (g) → 2 HCCCl (g)	Δ_rH°(0 K) = -0.76 ± 0.25 kcal/mol	Karton 2017, Karton 2011, Karton 2007, Karton 2006
0.391	2856.6	HCCNH (g) + CH4 (g) → CH3NH (g) + HCCH (g)	Δ_rH°(0 K) = 87.84 ± 1.5 kJ/mol	Klippenstein 2017
0.347	6678.12	HCCH (g) + FCCF (g) → 2 HCCF (g)	Δ_rH°(0 K) = -5.22 ± 0.20 kcal/mol	Karton 2011
0.327	6838.6	3 HCCH (g) → HCCCCCCH (g) + 2 H2 (g)	Δ_rH°(0 K) = -2.60 ± 2.00 kJ/mol	Klippenstein 2017
0.325	5365.6	HOCCOH (g) + HCCH (g) → 2 HCCOH (g, singlet)	Δ_rH°(0 K) = -20.17 ± 2.00 kJ/mol	Klippenstein 2017
0.293	6696.4	HCCH (g) + BrCCBr (g) → 2 HCCBr (g)	Δ_rH°(0 K) = 0.45 ± 1.0 kcal/mol	Ruscic G4
0.280	6674.2	HCCH (g) + 2 CH3Br (g) → BrCCBr (g) + 2 CH4 (g)	Δ_rH°(0 K) = 2.34 ± 1.0 kcal/mol	Ruscic G4
0.274	6837.6	HCCCCCCH (g) + HCCH (g) → 2 HCCCCH (g)	Δ_rH°(0 K) = 5.15 ± 2.00 kJ/mol	Klippenstein 2017
0.263	2608.6	HCCH (g) → HCCH (g, cis-triplet)	Δ_rH°(0 K) = 30900 ± 230 cm-1	Sherrill 2000
0.258	6848.4	HCCCCCCH (g) + CCH (g) → CCCCCCH (g) + HCCH (g)	Δ_rH°(0 K) = -3.84 ± 0.90 kcal/mol	Ruscic CBS-n
0.242	6696.3	HCCH (g) + BrCCBr (g) → 2 HCCBr (g)	Δ_rH°(0 K) = 0.65 ± 1.1 kcal/mol	Ruscic G3X
0.231	6674.1	HCCH (g) + 2 CH3Br (g) → BrCCBr (g) + 2 CH4 (g)	Δ_rH°(0 K) = 3.37 ± 1.1 kcal/mol	Ruscic G3X
0.218	6679.12	HCCH (g) + CH3F (g) → HCCF (g) + CH4 (g)	Δ_rH°(0 K) = 8.81 ± 0.20 kcal/mol	Karton 2011
0.216	3687.14	C (g) + HCCH (g) → CH(CC) (g) + H (g)	Δ_rH°(0 K) = -12.15 ± 1.5 kJ/mol	Klippenstein 2017
0.213	3490.5	CH3CHC (g, triplet) + HCCH (g) → CCH2 (g, triplet) + CH3CCH (g)	Δ_rH°(0 K) = -13.16 ± 0.85 kcal/mol	Ruscic W1RO
0.207	6229.1	HCCCl (g) + CH2CH2 (g) → CH2CHCl (g) + HCCH (g)	Δ_rH°(0 K) = -7.80 ± 0.25 kcal/mol	Karton 2017, Karton 2011, Karton 2007, Karton 2006

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. 1.176 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		T. L. Nguyen et al, ongoing studies (2024)
5		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]
6		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 [5] and Ruscic and Bross[6]).
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.