Iodine
- Formula: I2
- Molecular weight: 253.80894
- IUPAC Standard InChI: InChI=1S/I2/c1-2
- IUPAC Standard InChIKey: PNDPGZBMCMUPRI-UHFFFAOYSA-N
- CAS Registry Number: 7553-56-2
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript. - Other names: I2; Eranol; Iode; Iodine-127; Iodio; Iosan Superdip; Jod; Jood; Molecular iodine; Tincture iodine; Vistarin; Iodine crystals; Iodine sublimed; Diiodine; Diatomic iodine
- Permanent link for this species. Use this link for bookmarking this species for future reference.
- Information on this page:
- Other data available:
- Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 75
- Gas phase ion energetics data
- Constants of diatomic molecules
- Data at other public NIST sites:
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Gas phase thermochemistry data
Go To: Top, Condensed phase thermochemistry data, Phase change data, Henry's Law data, Ion clustering data, 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 | 62.42 ± 0.08 | kJ/mol | Review | Cox, Wagman, et al., 1984 | CODATA Review value |
| ΔfH°gas | 62.42 | kJ/mol | Review | Chase, 1998 | Data last reviewed in June, 1982 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 260.687 ± 0.005 | J/mol*K | Review | Cox, Wagman, et al., 1984 | CODATA Review value |
| S°gas,1 bar | 260.69 | J/mol*K | Review | Chase, 1998 | Data last reviewed in June, 1982 |
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 (J/mol*K)
H° = standard enthalpy (kJ/mol)
S° = standard entropy (J/mol*K)
t = temperature (K) / 1000.
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| Temperature (K) | 457.666 to 2000. | 2000. to 6000. |
|---|---|---|
| A | 37.79763 | 76.73414 |
| B | 0.225453 | -4.045782 |
| C | -0.912556 | -1.848145 |
| D | 1.034913 | 0.219044 |
| E | -0.083826 | -82.39384 |
| F | 50.86865 | -53.87151 |
| G | 305.9199 | 281.2267 |
| H | 62.42110 | 62.42110 |
| Reference | Chase, 1998 | Chase, 1998 |
| Comment | Data last reviewed in June, 1982 | Data last reviewed in June, 1982 |
Condensed phase thermochemistry data
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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°liquid | 13.52 | kJ/mol | Review | Chase, 1998 | Data last reviewed in June, 1982 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°liquid,1 bar | 150.36 | J/mol*K | Review | Chase, 1998 | Data last reviewed in June, 1982 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°solid,1 bar | 116.14 ± 0.30 | J/mol*K | Review | Cox, Wagman, et al., 1984 | CODATA Review value |
| Quantity | Value | Units | Method | Reference | Comment |
| S°solid | 116.14 | J/mol*K | Review | Chase, 1998 | Data last reviewed in June, 1982 |
Liquid 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 (J/mol*K)
H° = standard enthalpy (kJ/mol)
S° = standard entropy (J/mol*K)
t = temperature (K) / 1000.
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| Temperature (K) | 386.75 to 457.666 |
|---|---|
| A | 80.66919 |
| B | 6.855652×10-8 |
| C | -8.724352×10-8 |
| D | 3.723132×10-8 |
| E | 4.735829×10-10 |
| F | -10.52782 |
| G | 247.9798 |
| H | 13.52302 |
| Reference | Chase, 1998 |
| Comment | Data last reviewed in June, 1982 |
Solid 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 (J/mol*K)
H° = standard enthalpy (kJ/mol)
S° = standard entropy (J/mol*K)
t = temperature (K) / 1000.
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| Temperature (K) | 298. to 386.75 |
|---|---|
| A | -195.7635 |
| B | 918.8984 |
| C | -1079.242 |
| D | 534.3219 |
| E | 5.156403 |
| F | 43.29938 |
| G | -322.4780 |
| H | 0.000000 |
| Reference | Chase, 1998 |
| Comment | Data last reviewed in June, 1982 |
Phase change data
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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
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 |
|---|---|---|---|---|---|
| 311.9 to 456. | 3.36429 | 1039.159 | -146.589 | Stull, 1947 | Coefficents calculated by NIST from author's data. |
Henry's Law data
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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: Rolf Sander
Henry's Law constant (water solution)
kH(T) = k°H exp(d(ln(kH))/d(1/T) ((1/T) - 1/(298.15 K)))
k°H = Henry's law constant for solubility in water at 298.15 K (mol/(kg*bar))
d(ln(kH))/d(1/T) = Temperature dependence constant (K)
| k°H (mol/(kg*bar)) | d(ln(kH))/d(1/T) (K) | Method | Reference | Comment |
|---|---|---|---|---|
| 3.0 | 4400. | R | N/A | |
| 1.1 | C | N/A | missing citation quote a paper as the source that gives only the solubility but not the Henry's law constant. | |
| 3.3 | 4800. | T | N/A | |
| 3.1 | 4600. | R | N/A |
Ion clustering data
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Henry's Law 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 as indicated in comments:
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
B - John E. Bartmess
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
+
= (
•
)
By formula: I- + I2 = (I- • I2)
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 100. | kJ/mol | N/A | Downs and Adams, 1973 | gas phase; from ΔrH(f); M |
+
= I3-
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 136. ± 10. | kJ/mol | N/A | Taylor, Asmis, et al., 1999 | gas phase; B |
| ΔrH° | 126. ± 5.9 | kJ/mol | CIDT | Do, Klein, et al., 1997 | gas phase; B |
| ΔrH° | 356.1 | kJ/mol | Ther | Finch, Gates, et al., 1977 | gas phase; This value is far more bound than expected from other studies; B |
| ΔrH° | 136.4 | kJ/mol | N/A | Check, Faust, et al., 2001 | gas phase; FeF3-(t); ; ΔS(EA)=2.8; B |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | 94.14 | kJ/mol | N/A | Check, Faust, et al., 2001 | gas phase; FeF3-(t); ; ΔS(EA)=2.8; B |
By formula: I3- + I2 = (I3- • I2)
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 49.0 ± 5.9 | kJ/mol | CIDT | Do, Klein, et al., 1997 | gas phase; B |
References
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Henry's Law data, Ion clustering data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Cox, Wagman, et al., 1984
Cox, J.D.; Wagman, D.D.; Medvedev, V.A.,
CODATA Key Values for Thermodynamics, Hemisphere Publishing Corp., New York, 1984, 1. [all data]
Chase, 1998
Chase, M.W., Jr.,
NIST-JANAF Themochemical Tables, Fourth Edition,
J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]
Stull, 1947
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]
Downs and Adams, 1973
Downs, A.J.; Adams, G.J.,
Comprehensive Inorganic Chemistry, J. C. Bailar, H. J. Emeleus, R. Nyholm and A. F. Trotman - Dickerson, ed(s)., Pergamon Press, New York, 1973, 1543. [all data]
Taylor, Asmis, et al., 1999
Taylor, T.R.; Asmis, K.R.; Zanni, M.T.; Neumark, D.M.,
Characterization of the I-3 radical by anion photoelectron spectroscopy,
J. Chem. Phys., 1999, 110, 16, 7607-7609, https://doi.org/10.1063/1.478672
. [all data]
Do, Klein, et al., 1997
Do, K.; Klein, T.P.; Pommerening, C.A.; Sunderlin, L.S.,
A New Flowing Afterglow-Guided Ion Beam Tandem Mass Spectrometer. Applications to the Thermochemistry of Polyiodide Ions,
J. Am. Soc. Mass Spectrom., 1997, 8, 7, 688, https://doi.org/10.1016/S1044-0305(97)00116-5
. [all data]
Finch, Gates, et al., 1977
Finch, A.; Gates, P.N.; Peake, S.J.,
Thermochemistry of polyhalides. III. Cesium and rubidium tetrachloroiodates,
J. Inorg. Nucl. Chem., 1977, 39, 2135. [all data]
Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S.,
Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements,
J. Phys. Chem. A,, 2001, 105, 34, 8111, https://doi.org/10.1021/jp011945l
. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Henry's Law data, Ion clustering data, References
- Symbols used in this document:
S°gas,1 bar Entropy of gas at standard conditions (1 bar) S°liquid,1 bar Entropy of liquid at standard conditions (1 bar) S°solid Entropy of solid at standard conditions S°solid,1 bar Entropy of solid at standard conditions (1 bar) d(ln(kH))/d(1/T) Temperature dependence parameter for Henry's Law constant k°H Henry's Law constant at 298.15K ΔfH°gas Enthalpy of formation of gas at standard conditions ΔfH°liquid Enthalpy of formation of liquid at standard conditions ΔrG° Free energy of reaction at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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