Hydrogen cyanide

Formula: CHN
Molecular weight: 27.0253
IUPAC Standard InChI: InChI=1S/CHN/c1-2/h1H
IUPAC Standard InChIKey: LELOWRISYMNNSU-UHFFFAOYSA-N
CAS Registry Number: 74-90-8
Chemical structure:
This structure is also available as a 2d Mol file
Other names: Hydrocyanic acid; AC; Blausaeure (German); Carbon hydride nitride (CHN); Formic anammonide; Formonitrile; HCN; Prussic Acid; Cyclon; Acide cyanhydrique; Acido cianidrico; Aero Liquid HCN; Blausaeure; Blauwzuur; Cyaanwaterstof; Cyanwasserstoff; Cyclone B; Cyjanowodor; Evercyn; NA 1051; Prussic acid, unstabilized; Rcra waste number P063; UN 1051; Zaclondiscoids; Carbon hydride nitride; Zootic acid; Agent AC; Nitrilomethane
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Information on this page:
Other data available:
- Gas phase thermochemistry data
- Condensed phase thermochemistry data
- Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 92
- Henry's Law data
- IR Spectrum
- Mass spectrum (electron ionization)
- Gas Chromatography
Data at other public NIST sites:
- Microwave spectra (on physics lab web site)
- Gas Phase Kinetics Database
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Data at NIST subscription sites:

NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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Phase change data

Go To: Top, Gas phase ion energetics data, Ion clustering data, Vibrational and/or electronic energy levels, References, Notes

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
DH - Eugene S. Domalski and Elizabeth D. Hearing
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
T_boil	299.0 ± 0.5	K	AVG	N/A	Average of 15 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_fus	260. ± 1.	K	AVG	N/A	Average of 13 out of 14 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_triple	259.86	K	N/A	Giauque and Ruehrwein, 1939	Crystal phase 1 phase; Uncertainty assigned by TRC = 0.02 K; TRC

Enthalpy of vaporization

Δ_vapH (kJ/mol)	Temperature (K)	Method	Reference	Comment
25.217	298.85	N/A	Giauque and Ruehrwein, 1939, 2	P = 101.325 kPa.; DH
28.1	274.	A	Stephenson and Malanowski, 1987	Based on data from 259. to 299. K.; AC
27.8	313.	A	Stephenson and Malanowski, 1987	Based on data from 298. to 457. K.; AC
28.1	272.	N/A	Iwasaki and Date, 1975	Based on data from 257. to 315. K.; AC
28.0	277.	N/A	Lewis and Schutz, 1934	Based on data from 259. to 294. K.; AC
27.8	282.	N/A	Perry and Porter, 1926	Based on data from 265. to 300. K.; AC
28.1	272.	N/A	Sinozaki, Hara, et al., 1926	Based on data from 257. to 319. K.; AC
27.2	303.	MM	Sinozaki, Hara, et al., 1926	Based on data from 256. to 319. K.; AC

Entropy of vaporization

Δ_vapS (J/mol*K)	Temperature (K)	Reference	Comment
84.38	298.85	Giauque and Ruehrwein, 1939, 2	P; DH

Antoine Equation Parameters

log₁₀(P) = A − (B / (T + C))
P = vapor pressure (bar)
T = temperature (K)

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Temperature (K)	A	B	C	Reference	Comment
256.73 to 319.38	4.67417	1340.791	-11.592	Sinozaki, Hara, et al., 1926	Coefficents calculated by NIST from author's data.

Enthalpy of sublimation

Δ_subH (kJ/mol)	Temperature (K)	Method	Reference	Comment
35.6	248.	N/A	Stephenson and Malanowski, 1987	Based on data from 236. to 259. K.; AC
37.6	228.	A	Stull, 1947	Based on data from 202. to 254. K.; AC

Enthalpy of fusion

Δ_fusH (kJ/mol)	Temperature (K)	Reference	Comment
8.406	259.90	Giauque and Ruehrwein, 1939, 2	DH

Entropy of fusion

Δ_fusS (J/mol*K)	Temperature (K)	Reference	Comment
32.34	259.90	Giauque and Ruehrwein, 1939, 2	DH

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Gas phase ion energetics data

Go To: Top, Phase change data, Ion clustering data, Vibrational and/or electronic energy levels, References, Notes

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to CHN⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	13.60 ± 0.01	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	712.9	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	681.6	kJ/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
0.00156	N/A	Ard, Garrett, et al., 2009	B
>1.00171	EIAE	Tsuda, Yokohata, et al., 1971	From CH₃CN; G3MP2B3 calculations indicate that the anion is unbound by ca. 1 eV. Possibly C2H3- instead.; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
13.71	EI	Lageot, 1972	LLK
13.59 ± 0.01	PI	Dibeler and Liston, 1968	RDSH
13.60 ± 0.01	PE	Baker and Turner, 1968	RDSH
13.73 ± 0.09	EI	Varsel, Morrell, et al., 1960	RDSH
13.7 ± 0.1	EI	Kusch, Hustrulid, et al., 1937	RDSH
13.61	PE	Kreile, Schweig, et al., 1982	Vertical value; LBLHLM
13.607 ± 0.002	PE	Fridh and Asbrink, 1975	Vertical value; LLK
13.60	PE	Potts and Williams, 1974	Vertical value; LLK
13.61 ± 0.01	PE	Frost, Lee, et al., 1973	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C⁺	23.8 ± 0.5	?	EI	Kusch, Hustrulid, et al., 1937	RDSH
CH⁺	21.8 ± 0.5	N	EI	Kusch, Hustrulid, et al., 1937	RDSH
CN⁺	19.43 ± 0.01	H	PI	Berkowitz, Chupka, et al., 1969	RDSH
CN⁺	19.40 ± 0.02	H	PI	Dibeler and Liston, 1968	RDSH
CN⁺	20.1 ± 0.2	H	EI	Kusch, Hustrulid, et al., 1937	RDSH
H⁺	15.18 ± 0.02	CN^-	PI	Berkowitz, Chupka, et al., 1969	RDSH
H⁺	19.00 ± 0.01	CN	PI	Berkowitz, Chupka, et al., 1969	RDSH
NH⁺	24.9 ± 0.5	C	EI	Kusch, Hustrulid, et al., 1937	RDSH
N⁺	25.6 ± 0.5	CH	EI	Kusch, Hustrulid, et al., 1937	RDSH

De-protonation reactions

CN^- + = Hydrogen cyanide

By formula: CN^- + H⁺ = CHN

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1464. ± 4.2	kJ/mol	CIDT	Akin and Ervin, 2006	gas phase; B
Δ_rH°	1466.5 ± 0.71	kJ/mol	D-EA	Bradforth, Kim, et al., 1993	gas phase; B
Δ_rH°	1469. ± 8.8	kJ/mol	G+TS	Bartmess, Scott, et al., 1979	gas phase; value altered from reference due to change in acidity scale; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1433. ± 4.6	kJ/mol	H-TS	Akin and Ervin, 2006	gas phase; B
Δ_rG°	1435.8 ± 1.1	kJ/mol	H-TS	Bradforth, Kim, et al., 1993	gas phase; B
Δ_rG°	1438. ± 8.4	kJ/mol	IMRE	Bartmess, Scott, et al., 1979	gas phase; value altered from reference due to change in acidity scale; B

Ion clustering data

Go To: Top, Phase change data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References, Notes

Data compiled as indicated in comments:
B - John E. Bartmess
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

+ Hydrogen cyanide = ( • )

By formula: Br^- + CHN = (Br^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	81.2 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Δ_rH°	66.9 ± 8.4	kJ/mol	Est	Larson and McMahon, 1984	gas phase; Extrapolated from other halide data; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	82.8	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	56.5 ± 6.7	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • Hydrogen cyanide ) + = ( • 2)

By formula: (Br^- • CHN) + CHN = (Br^- • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	68.2 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.0	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	39.7	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 2 Hydrogen cyanide ) + = ( • 3)

By formula: (Br^- • 2CHN) + CHN = (Br^- • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	53.6 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.6	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	26.4	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 3 Hydrogen cyanide ) + = ( • 4)

By formula: (Br^- • 3CHN) + CHN = (Br^- • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	43.5 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.5	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	15.9	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 4 Hydrogen cyanide ) + = ( • 5)

By formula: (Br^- • 4CHN) + CHN = (Br^- • 5CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	34. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	77.4	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	10.9	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

+ Hydrogen cyanide = ( • )

By formula: CHO₂^- + CHN = (CHO₂^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	92.0	kJ/mol	PHPMS	Meot-ner, 1988	gas phase; M,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.	J/mol*K	N/A	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M
Δ_rS°	89.5	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	65.3 ± 6.7	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy of 22.0 eu assumed.; B

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
49.4	473.	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M

( • Hydrogen cyanide ) + = ( • 2)

By formula: (CHO₂^- • CHN) + CHN = (CHO₂^- • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	74.5	kJ/mol	PHPMS	Meot-ner, 1988	gas phase; M,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.	J/mol*K	N/A	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M
Δ_rS°	98.7	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	44.77	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
40.	350.	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M

CH₂N⁺ + Hydrogen cyanide = (CH₂N⁺ • )

By formula: CH₂N⁺ + CHN = (CH₂N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	109.	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; Δ_rH, Δ_rS too small compared with other nitrile dimers; M
Δ_rH°	126.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.2	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; Δ_rH, Δ_rS too small compared with other nitrile dimers; M
Δ_rS°	130.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M

(CH₂N⁺ • Hydrogen cyanide ) + = (CH₂N⁺ • 2)

By formula: (CH₂N⁺ • CHN) + CHN = (CH₂N⁺ • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	57.7	kJ/mol	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M

(CH₂N⁺ • 2 Hydrogen cyanide ) + = (CH₂N⁺ • 3)

By formula: (CH₂N⁺ • 2CHN) + CHN = (CH₂N⁺ • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	49.4	kJ/mol	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	100.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M

(CH₂N⁺ • 3 Hydrogen cyanide ) + = (CH₂N⁺ • 4)

By formula: (CH₂N⁺ • 3CHN) + CHN = (CH₂N⁺ • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	38.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	109.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1978	gas phase; M

(CH₂N⁺ • Hydrogen cyanide • ) + = (CH₂N⁺ • 2 • )

By formula: (CH₂N⁺ • CHN • H₂O) + CHN = (CH₂N⁺ • 2CHN • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	65.3	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n, Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	100.	J/mol*K	N/A	Meot-Ner (Mautner) and Speller, 1989	gas phase; n, Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	35.	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n, Entropy change calculated or estimated; M

(CH₂N⁺ • ) + Hydrogen cyanide = (CH₂N⁺ • • )

By formula: (CH₂N⁺ • H₂O) + CHN = (CH₂N⁺ • CHN • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	78.7	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	85.4	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

(CH₂N⁺ • 2) + Hydrogen cyanide = (CH₂N⁺ • • 2)

By formula: (CH₂N⁺ • 2H₂O) + CHN = (CH₂N⁺ • CHN • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	70.7	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	101.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

+ Hydrogen cyanide = ( • )

By formula: CH₃O⁺ + CHN = (CH₃O⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	86.2	kJ/mol	FA	Tanaka, Mackay, et al., 1978	gas phase; switching reaction(H2COH+)H2CO; Fehsenfeld, Dotan, et al., 1978, Cunningham, Payzant, et al., 1972; M

CH₄NO⁺ + Hydrogen cyanide = (CH₄NO⁺ • )

By formula: CH₄NO⁺ + CHN = (CH₄NO⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	80.8	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
40.	427.	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

CH₅O⁺ + Hydrogen cyanide = (CH₅O⁺ • )

By formula: CH₅O⁺ + CHN = (CH₅O⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	108.	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.5	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

CH₆N⁺ + Hydrogen cyanide = (CH₆N⁺ • )

By formula: CH₆N⁺ + CHN = (CH₆N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	87.0	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.8	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

CN^- + Hydrogen cyanide = (CN^- • )

By formula: CN^- + CHN = (CN^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	91. ± 15.	kJ/mol	IMRE	Larson and McMahon, 1987	gas phase; B,M
Δ_rH°	83.7 ± 8.4	kJ/mol	Est	Larson and McMahon, 1984	gas phase; B
Δ_rH°	86.6	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rH°	86.6	kJ/mol	PHPMS	Meot-ner, 1988	gas phase; M,B,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	86.2	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rS°	86.2	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Δ_rS°	86.2	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Δ_rS°	113.	J/mol*K	N/A	Larson and McMahon, 1987	gas phase; switching reaction,Thermochemical ladder(H2O), Entropy change calculated or estimated; Payzant, Yamdagni, et al., 1971; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	60.7 ± 4.2	kJ/mol	TDAs	Meot-ner, 1988	gas phase; B
Δ_rG°	57.3 ± 9.6	kJ/mol	IMRE	Larson and McMahon, 1987	gas phase; B,M
Δ_rG°	60.7 ± 6.7	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

(CN^- • Hydrogen cyanide ) + = (CN^- • 2)

By formula: (CN^- • CHN) + CHN = (CN^- • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	68.6	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rH°	68.6	kJ/mol	PHPMS	Meot-ner, 1988	gas phase; M,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.2	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rS°	91.2	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Δ_rS°	91.2	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	41.4	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

(CN^- • 2 Hydrogen cyanide ) + = (CN^- • 3)

By formula: (CN^- • 2CHN) + CHN = (CN^- • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	52.7	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rH°	52.7	kJ/mol	PHPMS	Meot-ner, 1988	gas phase; M,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	88.7	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rS°	88.7	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Δ_rS°	88.7	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	26.4	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

(CN^- • 3 Hydrogen cyanide ) + = (CN^- • 4)

By formula: (CN^- • 3CHN) + CHN = (CN^- • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	45.6	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rH°	45.6	kJ/mol	PHPMS	Meot-ner, 1988	gas phase; M,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	104.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rS°	104.	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Δ_rS°	104.	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	14.6	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

(CN^- • 4 Hydrogen cyanide ) + = (CN^- • 5)

By formula: (CN^- • 4CHN) + CHN = (CN^- • 5CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	41. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Δ_rH°	41.	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.5	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Δ_rS°	84.5	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	15.9	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

(CN^- • 5 Hydrogen cyanide ) + = (CN^- • 6)

By formula: (CN^- • 5CHN) + CHN = (CN^- • 6CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	85.4	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	10.0	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

(CN^- • 6 Hydrogen cyanide ) + = (CN^- • 7)

By formula: (CN^- • 6CHN) + CHN = (CN^- • 7CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	32. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	6.69	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
13.	238.	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M

(CN^- • Hydrogen cyanide • ) + = (CN^- • 2 • )

By formula: (CN^- • CHN • H₂O) + CHN = (CN^- • 2CHN • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	55.2	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	74.5	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

(CN^- • Hydrogen cyanide • 2) + = (CN^- • 2 • 2)

By formula: (CN^- • CHN • 2H₂O) + CHN = (CN^- • 2CHN • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	52.7	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
31.	262.	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

(CN^- • 2 Hydrogen cyanide • ) + = (CN^- • 3 • )

By formula: (CN^- • 2CHN • H₂O) + CHN = (CN^- • 3CHN • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	51.5	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
30.	262.	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

(CN^- • 3) + Hydrogen cyanide = (CN^- • • 3)

By formula: (CN^- • 3H₂O) + CHN = (CN^- • CHN • 3H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	54.8	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
33.	262.	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

+ Hydrogen cyanide = ( • )

By formula: C₂H₃O₂^- + CHN = (C₂H₃O₂^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	92.9 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	98.3	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M

( • Hydrogen cyanide ) + = ( • 2)

By formula: (C₂H₃O₂^- • CHN) + CHN = (C₂H₃O₂^- • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	69.5 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.5	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	44.35	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 2 Hydrogen cyanide ) + = ( • 3)

By formula: (C₂H₃O₂^- • 2CHN) + CHN = (C₂H₃O₂^- • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	61.9 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	107.	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	30.1	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 3 Hydrogen cyanide ) + = ( • 4)

By formula: (C₂H₃O₂^- • 3CHN) + CHN = (C₂H₃O₂^- • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	50.2 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	114.	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	16.3	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 4 Hydrogen cyanide ) + = ( • 5)

By formula: (C₂H₃O₂^- • 4CHN) + CHN = (C₂H₃O₂^- • 5CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	41. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	100.	J/mol*K	N/A	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	10.0	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
19.	213.	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M

C₂H₄N⁺ + Hydrogen cyanide = (C₂H₄N⁺ • )

By formula: C₂H₄N⁺ + CHN = (C₂H₄N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	92.5	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; CD3CNH+; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.7	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; CD3CNH+; M

C₂H₅O⁺ + Hydrogen cyanide = (C₂H₅O⁺ • )

By formula: C₂H₅O⁺ + CHN = (C₂H₅O⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	96.2	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	90.8	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

C₃H₂N⁺ + Hydrogen cyanide = (C₃H₂N⁺ • )

By formula: C₃H₂N⁺ + CHN = (C₃H₂N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	99.6	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	107.	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

+ Hydrogen cyanide = ( • )

By formula: C₃H₃N₂^- + CHN = (C₃H₃N₂^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	100.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.6	J/mol*K	PHPMS	Meot-Ner (Mautner), 1988	gas phase; M

C₃H₇⁺ + Hydrogen cyanide = (C₃H₇⁺ • )

By formula: C₃H₇⁺ + CHN = (C₃H₇⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	166.	kJ/mol	PHPMS	Meot-Ner (Mautner) and Sieck, 1991	gas phase; condensation; M
Δ_rH°	129.	kJ/mol	PHPMS	Meot-Ner (Mautner), 1978	gas phase; forms i-C3H7NCH+; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	189.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Sieck, 1991	gas phase; condensation; M
Δ_rS°	130.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1978	gas phase; forms i-C3H7NCH+; M

C₃H₇O⁺ + Hydrogen cyanide = (C₃H₇O⁺ • )

By formula: C₃H₇O⁺ + CHN = (C₃H₇O⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	85.4	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	98.7	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

C₃H₁₀N⁺ + Hydrogen cyanide = (C₃H₁₀N⁺ • )

By formula: C₃H₁₀N⁺ + CHN = (C₃H₁₀N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	70.3	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.2	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

C₄H₈N⁺ + Hydrogen cyanide = (C₄H₈N⁺ • )

By formula: C₄H₈N⁺ + CHN = (C₄H₈N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	84.1	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	94.1	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

C₄H₉⁺ + Hydrogen cyanide = (C₄H₉⁺ • )

By formula: C₄H₉⁺ + CHN = (C₄H₉⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	68.2	kJ/mol	PHPMS	Meot-Ner (Mautner), 1978	gas phase; may form t-C4H9NCH+; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	100.	J/mol*K	PHPMS	Meot-Ner (Mautner), 1978	gas phase; may form t-C4H9NCH+; M

C₄H₉O₂⁺ + Hydrogen cyanide = (C₄H₉O₂⁺ • )

By formula: C₄H₉O₂⁺ + CHN = (C₄H₉O₂⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	79.5	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.	J/mol*K	N/A	Speller and Meot-Ner (Mautner), 1985	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
33.	455.	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; Entropy change calculated or estimated; M

C₄H₁₀NO⁺ + Hydrogen cyanide = (C₄H₁₀NO⁺ • )

By formula: C₄H₁₀NO⁺ + CHN = (C₄H₁₀NO⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	66.1	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.4	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

C₇H₁₁O⁺ + Hydrogen cyanide = (C₇H₁₁O⁺ • )

By formula: C₇H₁₁O⁺ + CHN = (C₇H₁₁O⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	73.6	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	97.1	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

C₉H₂₂N⁺ + Hydrogen cyanide = (C₉H₂₂N⁺ • )

By formula: C₉H₂₂N⁺ + CHN = (C₉H₂₂N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	57.7	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	121.	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

+ Hydrogen cyanide = ( • )

By formula: Cl^- + CHN = (Cl^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	91.2 ± 4.2	kJ/mol	TDAs	Meot-ner, 1988	gas phase; B,B,M
Δ_rH°	87.9 ± 8.4	kJ/mol	IMRE	Larson and McMahon, 1984, 2	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.1	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Δ_rS°	99.2	J/mol*K	N/A	Larson and McMahon, 1984, 3	gas phase; switching reaction(Cl-)t-C4H9OH, Entropy change calculated or estimated; French, Ikuta, et al., 1982; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	67.8 ± 6.7	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B
Δ_rG°	67.4 ± 4.2	kJ/mol	TDAs	Meot-ner, 1988	gas phase; B
Δ_rG°	58.2 ± 8.4	kJ/mol	IMRE	Larson and McMahon, 1984, 2	gas phase; B,M

( • Hydrogen cyanide ) + = ( • 2)

By formula: (Cl^- • CHN) + CHN = (Cl^- • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	74.9 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.0	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	46.44	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 2 Hydrogen cyanide ) + = ( • 3)

By formula: (Cl^- • 2CHN) + CHN = (Cl^- • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	56.9 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	89.5	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	30.1	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 3 Hydrogen cyanide ) + = ( • 4)

By formula: (Cl^- • 3CHN) + CHN = (Cl^- • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	46.9 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	97.9	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	17.6	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 4 Hydrogen cyanide ) + = ( • 5)

By formula: (Cl^- • 4CHN) + CHN = (Cl^- • 5CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	37. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	89.1	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	10.5	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 5 Hydrogen cyanide ) + = ( • 6)

By formula: (Cl^- • 5CHN) + CHN = (Cl^- • 6CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	102.	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	6.28	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 6 Hydrogen cyanide ) + = ( • 7)

By formula: (Cl^- • 6CHN) + CHN = (Cl^- • 7CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	33. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	96.7	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	4.18	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 7 Hydrogen cyanide ) + = ( • 8)

By formula: (Cl^- • 7CHN) + CHN = (Cl^- • 8CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	34. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	115.	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.1 ± 9.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 8 Hydrogen cyanide ) + = ( • 9)

By formula: (Cl^- • 8CHN) + CHN = (Cl^- • 9CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	31. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	100.	J/mol*K	N/A	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	0.42	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy estimated; B

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
13.	171.	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; Entropy change calculated or estimated; M

+ Hydrogen cyanide = ( • )

By formula: F^- + CHN = (F^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	165. ± 8.4	kJ/mol	IMRE	Larson and McMahon, 1983	gas phase; These relative affinities are ca. 10 kcal/mol weaker than threshold values (see Wenthold and Squires, 1995) for donors greater than ca. 27 kcal/mol in free energy. This discrepancy has not yet been resolved, though the stronger value appears preferable.; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.9	J/mol*K	N/A	Larson and McMahon, 1983	gas phase; switching reaction(F-)H2O, Entropy change calculated or estimated; Arshadi, Yamdagni, et al., 1970; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	138. ± 8.4	kJ/mol	IMRE	Larson and McMahon, 1983	gas phase; These relative affinities are ca. 10 kcal/mol weaker than threshold values (see Wenthold and Squires, 1995) for donors greater than ca. 27 kcal/mol in free energy. This discrepancy has not yet been resolved, though the stronger value appears preferable.; B,M

HS^- + Hydrogen cyanide = (HS^- • )

By formula: HS^- + CHN = (HS^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	87.9 ± 4.2	kJ/mol	IMRE	Meot-ner, 1988	gas phase; See also H2S..CN-; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	PHPMS	Meot-ner, 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	62.8 ± 4.2	kJ/mol	IMRE	Meot-ner, 1988	gas phase; See also H2S..CN-; B

( • 2) + Hydrogen cyanide = ( • • 2)

By formula: (H₃O⁺ • 2H₂O) + CHN = (H₃O⁺ • CHN • 2H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	82.8	kJ/mol	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	123.	J/mol*K	PHPMS	Meot-Ner (Mautner) and Speller, 1989	gas phase; n; M

+ Hydrogen cyanide = ( • )

By formula: H₄N⁺ + CHN = (H₄N⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	91.6	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Δ_rH°	85.8	kJ/mol	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	97.9	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Δ_rS°	84.5	J/mol*K	PHPMS	Speller and Meot-Ner (Mautner), 1985	gas phase; M

( • Hydrogen cyanide ) + = ( • 2)

By formula: (H₄N⁺ • CHN) + CHN = (H₄N⁺ • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	72.8	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	97.9	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • 2 Hydrogen cyanide ) + = ( • 3)

By formula: (H₄N⁺ • 2CHN) + CHN = (H₄N⁺ • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	57.3	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	90.0	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • 3 Hydrogen cyanide ) + = ( • 4)

By formula: (H₄N⁺ • 3CHN) + CHN = (H₄N⁺ • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	46.0	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	87.4	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • 4 Hydrogen cyanide ) + = ( • 5)

By formula: (H₄N⁺ • 4CHN) + CHN = (H₄N⁺ • 5CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	33.	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.1	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • 5 Hydrogen cyanide ) + = ( • 6)

By formula: (H₄N⁺ • 5CHN) + CHN = (H₄N⁺ • 6CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	31.	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	83.3	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • Hydrogen cyanide • ) + = ( • 2 • )

By formula: (H₄N⁺ • CHN • H₃N) + CHN = (H₄N⁺ • 2CHN • H₃N)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	51.0	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	81.2	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • Hydrogen cyanide • 2) + = ( • 2 • 2)

By formula: (H₄N⁺ • CHN • 2H₃N) + CHN = (H₄N⁺ • 2CHN • 2H₃N)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	46.9	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
21.	315.	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated; M

( • 2 Hydrogen cyanide • ) + = ( • 3 • )

By formula: (H₄N⁺ • 2CHN • H₃N) + CHN = (H₄N⁺ • 3CHN • H₃N)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	53.6	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	101.	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • 3 Hydrogen cyanide • ) + = ( • 4 • )

By formula: (H₄N⁺ • 3CHN • H₃N) + CHN = (H₄N⁺ • 4CHN • H₃N)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36.	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated, T = 392 in paper is error; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated, T = 392 in paper is error; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
11.	292.	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated, T = 392 in paper is error; M

( • ) + Hydrogen cyanide = ( • • )

By formula: (H₄N⁺ • H₃N) + CHN = (H₄N⁺ • CHN • H₃N)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	59.4	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	77.4	J/mol*K	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; M

( • 2) + Hydrogen cyanide = ( • • 2)

By formula: (H₄N⁺ • 2H₃N) + CHN = (H₄N⁺ • CHN • 2H₃N)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	56.1	kJ/mol	PHPMS	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	76.6	J/mol*K	N/A	Deakyne, Knuth, et al., 1994	gas phase; Entropy change calculated or estimated; M

+ Hydrogen cyanide = ( • )

By formula: I^- + CHN = (I^- • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	70.3 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	88.7	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	43.5 ± 6.7	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • Hydrogen cyanide ) + = ( • 2)

By formula: (I^- • CHN) + CHN = (I^- • 2CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	55.2 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	83.7	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	30.1	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 2 Hydrogen cyanide ) + = ( • 3)

By formula: (I^- • 2CHN) + CHN = (I^- • 3CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	46.9 ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	87.9	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	20.5	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 3 Hydrogen cyanide ) + = ( • 4)

By formula: (I^- • 3CHN) + CHN = (I^- • 4CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	38. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.9	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	13.4	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 4 Hydrogen cyanide ) + = ( • 5)

By formula: (I^- • 4CHN) + CHN = (I^- • 5CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	36. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	95.8	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	7.53	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 5 Hydrogen cyanide ) + = ( • 6)

By formula: (I^- • 5CHN) + CHN = (I^- • 6CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	31. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	83.3	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	6.28	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 6 Hydrogen cyanide ) + = ( • 7)

By formula: (I^- • 6CHN) + CHN = (I^- • 7CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	31. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	83.3	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	6.28	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

( • 7 Hydrogen cyanide ) + = ( • 8)

By formula: (I^- • 7CHN) + CHN = (I^- • 8CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	28. ± 4.2	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B,M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	88.7	J/mol*K	PHPMS	Meot-ner, Cybulski, et al., 1988	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	2.1	kJ/mol	TDAs	Meot-ner, Cybulski, et al., 1988	gas phase; B

+ Hydrogen cyanide = ( • )

By formula: Li⁺ + CHN = (Li⁺ • CHN)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	152.	kJ/mol	ICR	Woodin and Beauchamp, 1978	gas phase; switching reaction(Li+)H2O, Entropy change calculated or estimated; Dzidic and Kebarle, 1970 interpolated; M
Δ_rH°	150.	kJ/mol	ICR	Staley and Beauchamp, 1975	gas phase; switching reaction(Li+)H2O, from graph; Dzidic and Kebarle, 1970 extrapolated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	100.	J/mol*K	N/A	Woodin and Beauchamp, 1978	gas phase; switching reaction(Li+)H2O, Entropy change calculated or estimated; Dzidic and Kebarle, 1970 interpolated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	120.	kJ/mol	ICR	Woodin and Beauchamp, 1978	gas phase; switching reaction(Li+)H2O, Entropy change calculated or estimated; Dzidic and Kebarle, 1970 interpolated; M

Vibrational and/or electronic energy levels

Go To: Top, Phase change data, Gas phase ion energetics data, Ion clustering data, References, Notes

Data compiled by: Takehiko Shimanouchi

Symmetry: C_∞ν Symmetry Number σ = 1

Sym.	No	Approximate	Selected Freq.		Infrared		Raman

Species		type of mode	Value	Rating	Value	Phase	Value	Phase

σ⁺	1	CH str	3311	A	3311.47 S	gas	3313 W	liq.
π	2	Bend	712	A	711.98 VS	gas	712 W	liq.
σ⁺	3	CN str	2097	A	2096.85 W	gas	2089 S	liq.

Source: Shimanouchi, 1972

Notes

Very strong

Strong

Weak

0~1 cm^-1 uncertainty

References

Go To: Top, Phase change data, Gas phase ion energetics data, Ion clustering data, Vibrational and/or electronic energy levels, Notes

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Giauque, W.F.; Ruehrwein, R.A., The entropy of hydrogen cyanide. Heat capacity, heat of vaporization and vapor pressure. Hydrogen bond polymerization of the gas in chains of indefinite length, J. Am. Chem. Soc., 1939, 61, 2626-2633. [all data]

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Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

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Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

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Lageot, C., Etude des etats excites de l'ion HCN⁺, J. Chim. Phys. Phys.-Chim. Biol., 1972, 68, 214. [all data]

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Dibeler, V.H.; Liston, S.K., Mass-spectrometric study of photoionization. IX. Hydrogen cyanide and acetonitrile, J. Chem. Phys., 1968, 48, 4765. [all data]

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Baker, C.; Turner, D.W., High resolution molecular photoelectron spectroscopy. III.Acetylenes and azaacetylenes, Proc. Roy. Soc. (London), 1968, A308, 19. [all data]

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Varsel, C.J.; Morrell, F.A.; Resnik, F.E.; Powell, W.A., Qualitative and quantitative analysis of organic compounds. Use of low-voltage mass spectrometry, Anal. Chem., 1960, 32, 182. [all data]

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Kusch, P.; Hustrulid, A.; Tate, J.T., The dissociation of HCN, C₂H₂, C₂N₂ and C₂H₄ by electron impact, Phys. Rev., 1937, 52, 843. [all data]

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Potts, A.W.; Williams, T.A., The observation of "forbidden" transitions in He II photoelectron spectra, J. Electron Spectrosc. Relat. Phenom., 1974, 3, 3. [all data]

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Frost, D.C.; Lee, S.T.; McDowell, C.A., The photoelectron spectrum of HCP and comments on the first photoelectron band of HCN, Chem. Phys. Lett., 1973, 23, 472. [all data]

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Akin, F.A.; Ervin, K.M., Collision-induced dissociation of HS-(HCN): Unsymmetrical hydrogen bonding in a proton-bound dimer anion, J. Phys. Chem. A, 2006, 110, 4, 1342-1349, https://doi.org/10.1021/jp0540454 . [all data]

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Bradforth, S.E.; Kim, E.H.; Arnold, D.W.; Neumark, D.M., Photoelectron Spectroscopy of CN-, NCO-, and NCS-, J. Chem. Phys., 1993, 98, 2, 800, https://doi.org/10.1063/1.464244 . [all data]

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Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr., The gas phase acidity scale from methanol to phenol, J. Am. Chem. Soc., 1979, 101, 6047. [all data]

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Larson, J.W.; McMahon, T.B., Gas phase bihalide and pseudohalide ions. An ICR determination of hydrogen bond energies in XHY- species (X,Y = F, Cl, Br, CN), Inorg. Chem., 1984, 23, 2029. [all data]

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Meot-ner, M., Ionic Hydrogen Bond and Ion Solvation. ₆. Interaction Energies of the Acetate Ion with Organic Molecules. Comparison of CH₃COO^- with Cl^-, CN^-, and SH^-, J. Am. Chem. Soc., 1988, 110, 12, 3854, https://doi.org/10.1021/ja00220a022 . [all data]

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Staley, R.H.; Beauchamp, J.L., Intrinsic Acid - Base Properties of Molecules. Binding Energies of Li+ to pi - and n - Donor Bases, J. Am. Chem. Soc., 1975, 97, 20, 5920, https://doi.org/10.1021/ja00853a050 . [all data]

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Notes

Go To: Top, Phase change data, Gas phase ion energetics data, Ion clustering data, Vibrational and/or electronic energy levels, References

Symbols used in this document:

AE	Appearance energy
EA	Electron affinity
IE (evaluated)	Recommended ionization energy
T	Temperature
T_boil	Boiling point
T_fus	Fusion (melting) point
T_triple	Triple point temperature
Δ_fusH	Enthalpy of fusion
Δ_fusS	Entropy of fusion
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_rS°	Entropy of reaction at standard conditions
Δ_subH	Enthalpy of sublimation
Δ_vapH	Enthalpy of vaporization
Δ_vapS	Entropy of vaporization

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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Hydrogen cyanide

Data at NIST subscription sites:

Phase change data

Enthalpy of vaporization

Entropy of vaporization

Antoine Equation Parameters

Enthalpy of sublimation

Enthalpy of fusion

Entropy of fusion

Gas phase ion energetics data

Electron affinity determinations

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

Ion clustering data

Clustering reactions

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Free energy of reaction

Vibrational and/or electronic energy levels

Symmetry: C∞ν Symmetry Number σ = 1

Notes

References

Notes

Symmetry: C_∞ν Symmetry Number σ = 1