potassium iodide
- Formula: IK
- Molecular weight: 166.0028
- IUPAC Standard InChI: InChI=1S/HI.K/h1H;/q;+1/p-1
- IUPAC Standard InChIKey: NLKNQRATVPKPDG-UHFFFAOYSA-M
- CAS Registry Number: 7681-11-0
- Chemical structure:
This structure is also available as a 2d Mol file - Permanent link for this species. Use this link for bookmarking this species for future reference.
- Information on this page:
- Other data available:
- Data at other public NIST sites:
- Options:
Gas phase thermochemistry data
Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, 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 | -125.52 | kJ/mol | Review | Chase, 1998 | Data last reviewed in June, 1967 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 258.28 | J/mol*K | Review | Chase, 1998 | Data last reviewed in June, 1967 |
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.
View plot Requires a JavaScript / HTML 5 canvas capable browser.
| Temperature (K) | 2500. to 6000. |
|---|---|
| A | 37.40622 |
| B | 0.828440 |
| C | -0.002031 |
| D | 0.000174 |
| E | -0.047344 |
| F | -136.8683 |
| G | 303.0375 |
| H | -125.5200 |
| Reference | Chase, 1998 |
| Comment | Data last reviewed in June, 1967 |
Condensed phase thermochemistry data
Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, 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°liquid | -312.85 | kJ/mol | Review | Chase, 1998 | Data last reviewed in June, 1967 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°liquid,1 bar | 114.10 | J/mol*K | Review | Chase, 1998 | Data last reviewed in June, 1967 |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔfH°solid | -327.90 | kJ/mol | Review | Chase, 1998 | Data last reviewed in June, 1967 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°solid | 106.37 | J/mol*K | Review | Chase, 1998 | Data last reviewed in June, 1967 |
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.
View plot Requires a JavaScript / HTML 5 canvas capable browser.
| Temperature (K) | 954. to 2500. |
|---|---|
| A | 72.38320 |
| B | -1.627693×10-9 |
| C | 1.020901×10-9 |
| D | -2.026337×10-10 |
| E | -4.120467×10-11 |
| F | -334.4271 |
| G | 201.6935 |
| H | -312.8465 |
| Reference | Chase, 1998 |
| Comment | Data last reviewed in June, 1967 |
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.
View plot Requires a JavaScript / HTML 5 canvas capable browser.
| Temperature (K) | 298. to 954. |
|---|---|
| A | 73.62376 |
| B | -85.43644 |
| C | 130.0973 |
| D | -48.86619 |
| E | -0.502415 |
| F | -348.7987 |
| G | 212.7614 |
| H | -327.9005 |
| Reference | Chase, 1998 |
| Comment | Data last reviewed in June, 1967 |
Phase change data
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, 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.
Antoine Equation Parameters
log10(P) = A − (B / (T + C))
P = vapor pressure (bar)
T = temperature (K)
View plot Requires a JavaScript / HTML 5 canvas capable browser.
| Temperature (K) | A | B | C | Reference | Comment |
|---|---|---|---|---|---|
| 1018. to 1597. | 4.40221 | 6421.797 | -136.338 | Stull, 1947 | Coefficents calculated by NIST from author's data. |
Reaction thermochemistry data
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, 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.
Data compiled by: John E. Bartmess
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.
Individual Reactions
+
= (
•
)
By formula: I- + IK = (I- • IK)
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 163. ± 8.8 | kJ/mol | N/A | Burdukovskaya, Kudin, et al., 1984 | gas phase; value altered from reference due to conversion from electron convention to ion convention |
Constants of diatomic molecules
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction 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 January, 1977
| 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Features in the elctron energy loss spectrum Geiger and Pfeiffer, 1968, Rudge, Trajmar, et al., 1976 at ~3.8, 4.7, 5.1 eV correspond to maxima in the absorption spectrum. Peaks at higher energies could indicate that KI absorbs strongly in the VUV region; structure above 19 eV may arise from excitation of a metal 3p electron. | ||||||||||||
| Continuous absorption 1 above 26500 cm-1, maxima at 30800, 38400, 41700 2 cm-1. | ||||||||||||
| ↳Muller, 1927; Levi, 1934; Davidovits and Brodhead, 1967 | ||||||||||||
| A (0+) | (26620) 3 | |||||||||||
| X 1Σ+ | 0 | 186.53 4 | 0.574 | 0.06087473 | 0.00026776 | 3.88E-7 | 2.5934E-8 | 4E-12 | 3.047844 5 | |||
| ↳Honig, Mandel, et al., 1954; Rusk and Gordy, 1962 | ||||||||||||
Notes
| 1 | Absorption cross sections Davidovits and Brodhead, 1967. A preliminary measurement of the photodissociation product anisotropy by photofragment spectroscopy at 28800 cm-1 Ormerod, Powers, et al., 1974 indicates strong contributions from perpendicular transitions. |
| 2 | Photodissociation produces K(4p 2P); similarly, photodissociation at 52600 cm-1 leads to K(5p 2P) Earl and Herm, 1974. |
| 3 | This is one of five very shallow states (0+, 0-, 1, 1, 2) 8 arising from normal products K (2S1/2) + I (2P3/2). The analysis of K-off-I differential elastic scattering measurements Kaufmann, Lawter, et al., 1974 suggests that only 0+ (De ~ 150 cm-1, re ~ 3.85 Å) is favorably situated for transitions from the ground state. Acordingly, Kaufmann, Kinsey, et al., 1974 have analyzed the fluctuation bands observed in absorption from 19600 to 27000 cm-1 Sommermeyer, 1929, Levi, 1934 and in chemiluminescence 9 from 16300 to 26200 cm-1 Levi, 1934, Kaufmann, Kinsey, et al., 1974, Oldenborg, Gole, et al., 1974 in terms of the A ↔ X transition, assigning vibrational quanutm numbers v" from 2 to 64, and constructing an accurate potential curve for the excited state. |
| 4 | missing note |
| 5 | Rotation spectrum 11 |
| 6 | Thermochemical value Brewer and Brackett, 1961; flame photometry Bulewicz, Phillips, et al., 1961 gives 3.49 eV. Earlier spectroscopic estimates were 3.31 eV Levi, 1934 and ≤ 3.47 eV Barrow and Caunt, 1953. |
| 7 | Adiabatic potential from the photoelectron spectrum Potts, Williams, et al., 1974, not corrected for thermal population of ground state vibrational levels; band maximum (vertical potential) at 7.68 eV. |
| 8 | A differential scattering experiment investigating the collisional depolarization of polarized K atoms missing citation leads to the conclusion that J,J coupling would provide the most adequate description of these states. |
| 9 | The actual onset and cutoff wavelengths depend on the experimental conditions: a beam-gas arrangement Oldenborg, Gole, et al., 1974 or flames Levi, 1934, Kaufmann, Kinsey, et al., 1974. |
| 10 | From the microwave results by use of Dunham's theory. |
| 11 | Quadrupole hyperfine structure Tiemann, Ali, et al., 1973. The dipole moment μel = 10.82 D Story and Hebert, 1976 was measured by the electric deflection method Story and Hebert, 1976; see also Rodebush, Murray, et al., 1936. |
| 12 | From D00(KI) + I.P.(K) - I.P.(KI); Potts, Williams, et al., 1974, give 0.37 eV. |
| 13 | From band maxima of the photoelectron spectrum Potts, Williams, et al., 1974, missing citation. |
References
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction 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]
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]
Burdukovskaya, Kudin, et al., 1984
Burdukovskaya, G.G.; Kudin, L.S.; Butman, M.F.; Krasnov, K.S.,
Ionic forms in the vapour over potassium iodide,
Russ. J. Inorg. Chem., 1984, 29, 3020. [all data]
Geiger and Pfeiffer, 1968
Geiger, J.; Pfeiffer, H.-C.,
Untersuchung der Anregung innerer Elektronen von Alkalihalogenidmolekulen im Energieverlustspektrum von 25 keV-Elektronen,
Z. Phys., 1968, 208, 105. [all data]
Rudge, Trajmar, et al., 1976
Rudge, M.R.H.; Trajmar, S.; Williams, W.,
Electron scattering by highly polar molecules. I. KI,
Phys. Rev. A: Gen. Phys., 1976, 13, 2074. [all data]
Muller, 1927
Muller, L.A.,
4. absorptionsspektren der alkalihalogenide in wasseriger losung und im dampf,
Ann. Phys. (Leipzig), 1927, 82, 39. [all data]
Levi, 1934
Levi,
Dissertation, Berlin, 1934, 0. [all data]
Davidovits and Brodhead, 1967
Davidovits, P.; Brodhead, D.C.,
Ultraviolet absorption cross sections for the alkali halide vapors,
J. Chem. Phys., 1967, 46, 2968. [all data]
Honig, Mandel, et al., 1954
Honig, A.; Mandel, M.; Stitch, M.L.; Townes, C.H.,
Microwave spectra of the alkali halides,
Phys. Rev., 1954, 96, 629. [all data]
Rusk and Gordy, 1962
Rusk, J.R.; Gordy, W.,
Millimeter wave molecular beam spectroscopy: alkali bromides and iodides,
Phys. Rev., 1962, 127, 817. [all data]
Ormerod, Powers, et al., 1974
Ormerod, R.C.; Powers, T.R.; Rose, T.L.,
Molecular-beam photodissociation studies of alkali iodides,
J. Chem. Phys., 1974, 60, 5109. [all data]
Earl and Herm, 1974
Earl, B.L.; Herm, R.R.,
Photodissociation of NaBr, Nal, and Kl vapors and collisional quenching of Na* (32P), K* (42P), and K* (52P) by foreign gases,
J. Chem. Phys., 1974, 60, 4568. [all data]
Kaufmann, Lawter, et al., 1974
Kaufmann, K.J.; Lawter, J.R.; Kinsey, J.L.,
Differential elastic scattering of potassium atoms by atomic iodine at thermal energies,
J. Chem. Phys., 1974, 60, 4016. [all data]
Kaufmann, Kinsey, et al., 1974
Kaufmann, K.J.; Kinsey, J.L.; Palmer, H.B.; Tewarson, A.,
Potassium iodide chemiluminescence in diffusion flames and the Kl upper-state potential,
J. Chem. Phys., 1974, 60, 4023. [all data]
Sommermeyer, 1929
Sommermeyer, K.,
Ein neues spektrum der gasformigen alkalihalogenide und seine deutung,
Z. Phys., 1929, 56, 548. [all data]
Oldenborg, Gole, et al., 1974
Oldenborg, R.C.; Gole, J.L.; Zare, R.N.,
Chemiluminescent spectra of alkali-halogen reactions,
J. Chem. Phys., 1974, 60, 4032. [all data]
Brewer and Brackett, 1961
Brewer, L.; Brackett, E.,
The dissociation energies of gaseous alkali halides,
Chem. Rev., 1961, 61, 425. [all data]
Bulewicz, Phillips, et al., 1961
Bulewicz, E.M.; Phillips, L.F.; Sugden, T.M.,
Determination of dissociation constants and heats of formation of simple molecules by flame photometry. Part 8. Stabilities of the gaseous diatomic halides of certain metals,
Trans. Faraday Soc., 1961, 57, 921. [all data]
Barrow and Caunt, 1953
Barrow, R.F.; Caunt, A.D.,
The ultra-violet absorption spectra of some gaseous alkali-metal halides and the dissociation energy of fluorine,
Proc. R. Soc. London A, 1953, 219, 120. [all data]
Potts, Williams, et al., 1974
Potts, A.W.; Williams, T.A.; Price, W.C.,
Photoelectron spectra and electronic structure of diatomic alkali halides,
Proc. Roy. Soc. London A, 1974, 341, 147. [all data]
Tiemann, Ali, et al., 1973
Tiemann, E.; Ali, H.El.; Hoeft, J.; Torring, T.,
Hyperfeinstruktur von KJ,
Z. Naturforsch. A, 1973, 28, 1058. [all data]
Story and Hebert, 1976
Story, T.L., Jr.; Hebert, A.J.,
Dipole moments of KI, RbBr, RbI, CsBr, and CsI by the electric deflection method,
J. Chem. Phys., 1976, 64, 855. [all data]
Rodebush, Murray, et al., 1936
Rodebush, W.H.; Murray, L.A., Jr.; Bixler, M.E.,
The dipole moments of the alkali halides,
J. Chem. Phys., 1936, 4, 372. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Constants of diatomic molecules, 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 ΔfH°gas Enthalpy of formation of gas at standard conditions ΔfH°liquid Enthalpy of formation of liquid at standard conditions ΔfH°solid Enthalpy of formation of solid at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
- The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
- Customer support for NIST Standard Reference Data products.