Magnesium monohydride
- Formula: HMg
- Molecular weight: 25.3129
- IUPAC Standard InChI: InChI=1S/Mg.H
- IUPAC Standard InChIKey: RZCHRULKKYOSQS-UHFFFAOYSA-N
- CAS Registry Number: 14332-53-7
- Chemical structure:
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Gas phase thermochemistry data
Go To: Top, 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 | 40.399 | kcal/mol | Review | Chase, 1998 | Data last reviewed in December, 1966 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 46.176 | cal/mol*K | Review | Chase, 1998 | Data last reviewed in December, 1966 |
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 (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/mol*K)
t = temperature (K) / 1000.
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| Temperature (K) | 298. to 1200. | 1200. to 6000. |
|---|---|---|
| A | 4.663411 | 9.492271 |
| B | 7.730120 | -0.244923 |
| C | -5.248719 | 0.099833 |
| D | 1.339141 | -0.002771 |
| E | 0.047494 | -0.895502 |
| F | 38.86931 | 35.64501 |
| G | 50.00371 | 55.28719 |
| H | 40.40010 | 40.40010 |
| Reference | Chase, 1998 | Chase, 1998 |
| Comment | Data last reviewed in December, 1966 | Data last reviewed in December, 1966 |
Constants of diatomic molecules
Go To: Top, Gas phase 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 March, 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Unidentified line structure at 42570 cm-1 [em. and abs., Guntsch, 1934 Guntsch, 1935 Turner and Harris, 1937 Guntsch, 1939] and 43180 - 43520 cm-1 [abs., Khan, 1962]. | ||||||||||||
| I (2Π) | [5.96] | [2E-4] | [1.710] | I ← X V | 47997.6 Z | |||||||
| ↳Khan, 1962 | ||||||||||||
| H (2Σ+) 1 | H ← X R | 47543 (Z) | ||||||||||
| ↳Khan, 1962 | ||||||||||||
| G (2Σ+) 2 | G ← X V | 46082 (Z) | ||||||||||
| ↳Khan, 1962 | ||||||||||||
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
| D 2Σ- | (42065) | (1630) 3 | [6.296] 4 | [3.8E-4] | [1.664] | D → A V | 22861.5 5 | |||||
| ↳Guntsch, 1937; Guntsch, 1939 | ||||||||||||
| C 2Π(r) | (41164) 6 | [1623.4] Z | 6.161 7 | 0.144 | 3.0E-4 | 1.682 | C → A | 21956.5 5 | ||||
| ↳Pearse, 1929; Guntsch, 1934; Guntsch, 1937, 2; Guntsch, 1939 | ||||||||||||
| C ↔ X V | 41235.9 Z | |||||||||||
| ↳missing citation; Guntsch, 1935; Grundstrom, 1936; Guntsch, 1937, 2; Turner and Harris, 1937; Guntsch, 1939; missing citation | ||||||||||||
| E 2Σ+ | (35568) | [1444.8] Z | 8 | 6.23 | 0.30 9 | [3.3E-4] 10 | 1.673 | E ← X VR | 35550.6 Z | |||
| ↳Khan, 1961; missing citation; Balfour and Cartwright, 1975 | ||||||||||||
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
| B' 2Σ+ | 22410.5 | 828.0 Z | 11.6 11 | [2.596] | 12 | 1.2E-4 | 0.13E-4 | 2.597 | B' → X R | 22081.9 Z | ||
| ↳Balfour and Cartwright, 1975; Balfour and Cartwright, 1976 | ||||||||||||
| A 2Πr | 19226.8 13 | 1598.17 Z | 31.085 14 | -0.633 | 6.1913 | 0.1931 15 | 0.0005 | 3.60E-4 16 | 1.6778 | A ↔ X 17 18 V | 19278.4 5 | |
| ↳Guntsch, 1937; Guntsch, 1939; Balfour, 1970; Balfour, 1970, 2; Balfour and Cartwright, 1976, 2 | ||||||||||||
| X 2Σ+ | 0 | 1495.20 Z | 31.889 19 | 0.384 | 5.8257 | 0.1859 20 | 3.44E-4 16 | 1.7297 21 | ||||
| ↳Knight and Weltner, 1971 | ||||||||||||
Notes
| 1 | R shaded band with head at 2100 Å. |
| 2 | V shaded band with head at 2172 Å. |
| 3 | Estimated from w2 = 4B3/D and from the observed isotope shift of the 0-0 band. |
| 4 | Spin doubling. |γ| = 0.01. |
| 5 | Average of the two subband origins Guntsch, 1939. |
| 6 | A0 = (+)3.7; Balfour, 1970, 2 gives -3.7, but his arguments are not conclusive. |
| 7 | The P and R branches of the C→X, 0-0 band break off above N' = 10; bands with v'>0 have Q branches only. The predissociation is caused by B' 2Σ+; see Balfour and Cartwright, 1975. |
| 8 | ΔG(3/2)= 1490. The v=2 level was formerly believed to be v=0 of a new 2Σ state (B 2Σ+), see Grundstrom, 1936, Grundstrom, 1936, 2, Guntsch, 1938, Guntsch, 1939. Similarly, Khan, 1961 assigned the 1-0 band as 0-0 of a new system F←X. |
| 9 | B2 = 5.448; see 8. Transitions to v=1 are discrete but those to v=2 are diffuse indicating that the state causing the predissociation [B' 2Σ+, see Balfour and Cartwright, 1975] crosses the E state potential curve between v=1 and 2. Emissions from v=2 has been observed at high pressure. |
| 10 | D1 = 4.0E-4; D2 = 2.71E-4; H2 = +8.6E-8; (see 8). |
| 11 | The equilibrium constants in Balfour and Cartwright, 1976 do not reproduce the observed intervals, probably owing to an error in ωeze. De ~ 10900 cm-1 Balfour and Cartwright, 1976 |
| 12 | Bv(v=1,2,3,4...9) = 2.605, 2.618, 2.608, 2.592, ... 2.419; Be = 2.585, but the higher order constants of Balfour and Cartwright, 1976 do no reproduce their data. Small perturbations by A 2Π. RKR potential curve Balfour and Cartwright, 1976. See also Sink, Bandrauk, et al., 1976. |
| 13 | A0= +35.3 Balfour, 1970, 2 |
| 14 | These constants (for v≤3) have been recalculated from the three ΔG values obtained by Balfour and Cartwright, 1976, 2; the equilibrium constants determined by Balfour and Cartwright, 1976, 2 do not reproduce their data. De ~ 14200 cm-1 Balfour and Cartwright, 1976, 2. |
| 15 | Small perturbations by B' 2Σ+. |
| 16 | Dv increases rapidly with v. |
| 17 | Oscillator strength f00= 0.257 [see Balfour and Cartwright, 1976, 2 and references given there], much larger than the earlier experimental value of Main, Carlson, et al., 1967. |
| 18 | Balfour, 1970 has measured the 0-0 and 0-1 bnads of 25MgH and 26MgH; see also Branch, 1970, Boyer, 1971. |
| 19 | ωeze= -0.113 Balfour and Cartwright, 1976, 2; De0 ~ 11700 cm-1 Balfour and Cartwright, 1976, 2. |
| 20 | +0.00393(v+1/2)2 - 0.00123(v+1/2)3. The last term was not reported by Balfour and Cartwright, 1976, 2 but must be included for a satisfactory fit to their data (v=0...6). |
| 21 | ESR sp. 23 |
| 22 | From extrapolations of the vibrational levels in X, A and B'. Close agreement with the theoretical value of Meyer and Rosmus, 1975, D0 = 1.25 eV. |
| 23 | In Ar matrices at 4K. |
References
Go To: Top, Gas phase 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]
Guntsch, 1934
Guntsch, A.,
Uber das bandenspektrum des magnesiumhydrids,
Z. Phys., 1934, 87, 312. [all data]
Guntsch, 1935
Guntsch, A.,
Uber das ultraviolette bandenspektrum des magnesiumhydrids und magnesiumdeutrids,
Z. Phys., 1935, 93, 534. [all data]
Turner and Harris, 1937
Turner, L.A.; Harris, W.T.,
The ultraviolet bands of magnesium hydride,
Phys. Rev., 1937, 52, 626. [all data]
Guntsch, 1939
Guntsch,
Dissertation, Stockholm, 1939, 1. [all data]
Khan, 1962
Khan, M.A.,
MgH bands at 2172, 2100 and 2088 Å and MgD bands at 2172, 2358 and 2364 A,
Proc. Phys. Soc. London, 1962, 80, 209. [all data]
Guntsch, 1937
Guntsch, A.,
Neue untersuchungen uber das bandenspektrum des magnesiumhydrids,
Z. Phys., 1937, 104, 584. [all data]
Pearse, 1929
Pearse, R.W.B.,
The ultra-violet spectrum of magnesium hydride. 1. The band at λ2430,
Proc. R. Soc. London A, 1929, 122, 442. [all data]
Guntsch, 1937, 2
Guntsch, A.,
Uber einige neue banden des magnesiumhydrids,
Z. Phys., 1937, 107, 420. [all data]
Grundstrom, 1936
Grundstrom,
Dissertation, Stockholm, 1936, 0. [all data]
Khan, 1961
Khan, M.A.,
MgH and MgD bands at 2819 Å and 2702 Å,
Proc. Phys. Soc. London, 1961, 77, 1133. [all data]
Balfour and Cartwright, 1975
Balfour, W.J.; Cartwright, H.M.,
Low-lying electronic states of magnesium hydride,
Chem. Phys. Lett., 1975, 32, 82. [all data]
Balfour and Cartwright, 1976
Balfour, W.J.; Cartwright, H.M.,
The B'2Σ+ → X2Σ+ systems of MgH and MgD,
Can. J. Phys., 1976, 54, 1898. [all data]
Balfour, 1970
Balfour, W.J.,
The A2Π → X2Σ+ systems of 24MgH, 25MgH, and 26MgH,
Astrophys. J., 1970, 162, 1031. [all data]
Balfour, 1970, 2
Balfour, W.J.,
The electronic spectrum of magnesium hydride and magnesium deuteride,
J. Phys. B:, 1970, 3, 1749. [all data]
Balfour and Cartwright, 1976, 2
Balfour, W.J.; Cartwright, H.M.,
The A2Π-X2Σ+ system and dissociation energy of magnesiun hydride,
Astron. Astrophys. Suppl. Ser., 1976, 26, 389. [all data]
Knight and Weltner, 1971
Knight, L.B., Jr.; Weltner, W., Jr.,
Hyperfine interaction and chemical bonding in MgH, CaH, SrH, and BaH molecules,
J. Chem. Phys., 1971, 54, 3875. [all data]
Grundstrom, 1936, 2
Grundstrom, B.,
Absorption spectrum of magnesium hydride in the ultra-violet,
Nature (London), 1936, 131, 108. [all data]
Guntsch, 1938
Guntsch, A.,
Druckeffekt in der magnesiumhydridbande bei λ2590 Å,
Z. Phys., 1938, 110, 549. [all data]
Sink, Bandrauk, et al., 1976
Sink, M.L.; Bandrauk, A.D.; Henneker, W.H.; Lefebvre-Brion, H.; Raseev, G.,
Theoretical study of the low-lying electronic states of MgH,
Chem. Phys. Lett., 1976, 39, 505. [all data]
Main, Carlson, et al., 1967
Main, R.P.; Carlson, D.J.; DuPuis, R.A.,
Measurement of oscillator strengths of the MgO(B1Σ+ - X1Σ+) and MgH(A2Π - X2Σ+) band systems,
J. Quant. Spectrosc. Radiat. Transfer, 1967, 7, 805. [all data]
Branch, 1970
Branch, D.,
Isotopes of magnesium in the sun,
Astrophys. J., 1970, 159, 39. [all data]
Boyer, 1971
Boyer, R.,
Isotopic lines of the MgH molecule,
Astron. Astrophys., 1971, 12, 464. [all data]
Meyer and Rosmus, 1975
Meyer, W.; Rosmus, P.,
PNO-Cl and CEPA studies of electron correlation effects. III. Spectroscopic constants and dipole moment functions for the ground states of the first-row and second-row diatomic hydrides,
J. Chem. Phys., 1975, 63, 2356. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Constants of diatomic molecules, References
- Symbols used in this document:
S°gas,1 bar Entropy of gas at standard conditions (1 bar) ΔfH°gas Enthalpy of formation of gas at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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