Calcium monohydride

Formula: CaH
Molecular weight: 41.086
IUPAC Standard InChI: InChI=1S/Ca.H
IUPAC Standard InChIKey: PKHCKQOIOXDRJH-UHFFFAOYSA-N
CAS Registry Number: 14452-75-6
Chemical structure:
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Reaction thermochemistry data

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Individual Reactions

Ca^- + = Calcium monohydride

By formula: Ca^- + H⁺ = HCa

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1476.1 ± 3.9	kJ/mol	D-EA	Petrunin, Andersen, et al., 1996	gas phase
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1452. ± 4.2	kJ/mol	H-TS	Petrunin, Andersen, et al., 1996	gas phase

Gas phase ion energetics data

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Data compiled as indicated in comments:
B - John E. Bartmess
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi

Electron affinity determinations

EA (eV)	Method	Reference	Comment
0.930 ± 0.050	PD	Rackwitz, Feldman, et al., 1977	B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
5.86 ± 0.09	S	Kaving and Lindgren, 1974	LLK

De-protonation reactions

Ca^- + = Calcium monohydride

By formula: Ca^- + H⁺ = HCa

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1476.1 ± 3.9	kJ/mol	D-EA	Petrunin, Andersen, et al., 1996	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1452. ± 4.2	kJ/mol	H-TS	Petrunin, Andersen, et al., 1996	gas phase; B

Constants of diatomic molecules

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Data compiled by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through July, 1976

Symbols used in the table of constants
Symbol	Meaning
State	electronic state and / or symmetry symbol
T_e	minimum electronic energy (cm^-1)
ω_e	vibrational constant – first term (cm^-1)
ω_ex_e	vibrational constant – second term (cm^-1)
ω_ey_e	vibrational constant – third term (cm^-1)
B_e	rotational constant in equilibrium position (cm^-1)
α_e	rotational constant – first term (cm^-1)
γ_e	rotation-vibration interaction constant (cm^-1)
D_e	centrifugal distortion constant (cm^-1)
β_e	rotational constant – first term, centrifugal force (cm^-1)
r_e	internuclear distance (Å)
Trans.	observed transition(s) corresponding to electronic state
ν₀₀	position of 0-0 band (units noted in table)

Diatomic constants for ⁴⁰CaH
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
I (²Σ)					[(4.60)]					[(1.93)]	I ← X	(39477)
I (²Σ)	↳Khan and Afridi, 1968
H (²Σ)					[(4.41)]					[(1.97)]	H ← X	(38798)
H (²Σ)	↳Khan and Afridi, 1968
F ²Σ⁺	36705	1487 1	28		[4.6867]			[0.0002017]		[1.9128]	F ← X V	36979.05 Z
F ²Σ⁺	↳Khan, 1962; missing citation; Khan and Afridi, 1968
M ²Δ (4d)	2				[4.89] 3					[1.87]	M ← X	35481.8 3
M ²Δ (4d)	↳missing citation
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
J ²Π (4d)	2				[4.89₈] 3			[2.8] 3		[1.87₁]	J ← X	35068.5₃ 3
J ²Π (4d)	↳missing citation
G ²Σ⁺ (4d)	(34735) 2	[1458] 4			[4.765] 3			[1.1₇] 3		[1.897]	G ← X	34819.5 3
G ²Σ⁺ (4d)	↳missing citation
L ²Π (5p)	(32680) 5	[1407.6] 6			[4.620₄] 6	0.113₉		[1.92₀] 6 7		1.914₈	L ← X	32739.3₇ 6
L ²Π (5p)	↳missing citation
K ²Σ⁺ (5p)	(32640)	[(1391)] 6			[4.601] 6 8	(0.085)		[1.93] 6 9		1.922	K ← X	32691.1 6
K ²Σ⁺ (5p)	↳missing citation
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
C ²Σ⁺	28276	1445 H	25		[4.58] 10 11			[1.7] 10		[1.94]	C ↔ X V	28348 10
C ²Σ⁺	↳missing citation; missing citation; Grundstrom, 1935
D ²Σ⁺	22602	1150 Z	33.₀		2.50 12	0.01				2.62	D → X R	22524 Z
D ²Σ⁺	↳Grundstrom, 1931; Grundstrom, 1932
E ²Π	20418 13	1248.₆ H^Q	21.₈		[4.284]			[2.2]		[2.001]	E → X 14 V	20392 Z
E ²Π	↳Watson and Weber, 1935
B ²Σ⁺ (4p)	15762	1285	20		[4.3410] 15	0.116		[2.020] 15 16		1.974₄	B ↔ X V	15754.9₆ 15
B ²Σ⁺ (4p)	↳Hulthen, 1927; Watson and Bender, 1930; missing citation; Liberale and Weniger, 1969; Berg and Klynning, 1974; Berg and Klynning, 1974, 2
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
A ²Π_r (4p)	14413 17	1333	20		[4.3476₉] 15	0.106		[1.883] 15 18		1.974₀	A ↔ X V	14430.39 15
A ²Π_r (4p)	↳Hulthen, 1927; Watson and Bender, 1930; Mulliken and Christy, 1931; Liberale and Weniger, 1969; Berg and Klynning, 1974; Berg and Klynning, 1974, 2
X ²Σ⁺	0	1298.34 Z	19.10		4.2766 19	0.0970		1.837 20		2.0025 21

Notes

From isotope relations Edvinsson, Kopp, et al., 1963.

A₀ = +5.0.

Deperturbed constants for the three interacting states which form the d complex. The ²Δ_5/2 component was not observed. Most of the lines are somewhat diffuse. The ²Π-²Σ band whose low J lines are sharp had been misinterpreted by Khan and Hasnain, 1973 in terms of two overlapping 2Σ-2Σ transitions. Small local perturbations.

From the proposed assignment of the 1-0 band by Khan and Afridi, 1968. Kaving and Lindgren, 1974 observe a diffuse single branch only.

A₀= +18.8, A₁= +19.3.

Deperturbed constants for the two interacting states which form the p complex. Small local perturbations.

D₁ = 2.06₄E-4; H₀ = +4.7E-9.

F₁ levels not observed, presumably on account of predissociation. In v=1 both spin components seem to be predissociated.

H₀= +2.5E-9.

Constants derived from high N values. At low N, v=0 is perturbed by a state of smaller B value. The observed origin of the 0-0 band is at 28352.5 cm^-1.

At low pressure predissociation above v=0, N=10.

Strong perturbations for higher N values.

A ~ 9.3.

Two Q heads.

Deperturbed constants for the strongly interacting states A ²Π and B ²Σ⁺: see Berg and Klynning, 1974. For an extensive discussion of the rotational structure of the two states (including spin and Λ-type doubling) see also Veseth, 1971, Veseth, 1971, 2, Veseth, 1971, 3.

H₀= +4.3₁E-9.

A₀= +79.01; slight J dependence Berg and Klynning, 1974. See also Veseth, 1971.

H₀= +5.08E-9.

Spin-splitting constant γ_v= +0.042₉ - 0.0010(v+1/2).

H_e= +5.51E-9.

ESR sp. 24

From the predissociation in C ²Σ⁺, assuming dissociation into Ca(³P) + H(²S).

From the observation of Rydberg states in the absorption spectrum Kaving and Lindgren, 1974.

In Ar matrix at 4 K Knight and Weltner, 1971.

References

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Petrunin, Andersen, et al., 1996
Petrunin, V.V.; Andersen, H.H.; Balling, P.; Andersen, T., Structural Properties of the Negative Calcium Ion: Binding Energies and Fine-structure Splitting, Phys. Rev. Lett., 1996, 76, 5, 744, https://doi.org/10.1103/PhysRevLett.76.744 . [all data]

Rackwitz, Feldman, et al., 1977
Rackwitz, R.; Feldman, D.; Kaiser, H.J.; Heincke, E., Photodetachment bei einigen zweiatomigen negativen hydridionen: BeH-, MgH-, CaH-, ZnH-, PH-, AsH-, Z. Naturforsch. A:, 1977, 32, 594. [all data]

Kaving and Lindgren, 1974
Kaving, B.; Lindgren, B., Ultraviolet absorption spectrum of the CaH molecule. II. The structure of the d-complex around 2850 A, Phys. Scr., 1974, 10, 81. [all data]

Khan and Afridi, 1968
Khan, M.A.; Afridi, M.K., A high dispersion study of some new absorption bands of CaH and CaD in the ultra-violet region, J. Phys. B:, 1968, 1, 260. [all data]

Khan, 1962
Khan, M.A., A new band in CaH at 2720 Å and discussion of the hydrides of metals of group II, Proc. Phys. Soc. London, 1962, 80, 593. [all data]

Grundstrom, 1935
Grundstrom, B., Die bandenspektra des calciumhydrids. III, Z. Phys., 1935, 95, 574. [all data]

Grundstrom, 1931
Grundstrom, B., Die bandenspektra des calciumhydrids. I., Z. Phys., 1931, 69, 235. [all data]

Grundstrom, 1932
Grundstrom, B., Die bandenspektra des calciumhydrids. II, Z. Phys., 1932, 75, 302. [all data]

Watson and Weber, 1935
Watson, W.W.; Weber, R.L., The E band system of calcium hydride, Phys. Rev., 1935, 48, 732. [all data]

Hulthen, 1927
Hulthen, E., On the band spectrum of calcium hydride, Phys. Rev., 1927, 29, 97. [all data]

Watson and Bender, 1930
Watson, W.W.; Bender, W., The Zeeman effect in the red CaH bands, Phys. Rev., 1930, 35, 1513. [all data]

Liberale and Weniger, 1969
Liberale, G.; Weniger, S., Etude du spectre d'absorption des systemes A²Π-X²Σ et B²Σ-X²Σ de l'hydrure de calcium, Physica (Amsterdam), 1969, 41, 47. [all data]

Berg and Klynning, 1974
Berg, L.-E.; Klynning, L., Rotational analysis of the A-X and B-X band systems of CaH, Phys. Scr., 1974, 10, 331. [all data]

Berg and Klynning, 1974, 2
Berg, L.-E.; Klynning, L., New laboratory measurments of the A²Π-X²Σ and B²Σ-X²Σ transitions of CaH, Astron. Astrophys. Suppl. Ser., 1974, 13, 325. [all data]

Mulliken and Christy, 1931
Mulliken, R.S.; Christy, A., Λ-type doubling and electron configurations in diatomic molecules, Phys. Rev., 1931, 38, 87. [all data]

Edvinsson, Kopp, et al., 1963
Edvinsson, G.; Kopp, I.; Lindgren, B.; Aslund, N., Rotational analysis of an ultraviolet system of the hydrides and deuterides of Ca, Sr and Ba, Ark. Fys., 1963, 25, 95. [all data]

Khan and Hasnain, 1973
Khan, M.A.; Hasnain, S.S., Two overlapping systems of CaH and CaD in the UV region, Nuovo Cimento B, 1973, 18, 384. [all data]

Veseth, 1971
Veseth, L., Corrections to the spin-orbit splitting in ²Π states of diatomic molecules, J. Mol. Spectrosc., 1971, 38, 228. [all data]

Veseth, 1971, 2
Veseth, L., An investigation of the interaction between close-lying ²Σ and ²Π states of diatomic molecules. I. Spin-splitting of the ²Σ levels, Mol. Phys., 1971, 20, 1057. [all data]

Veseth, 1971, 3
Veseth, L., An investigation of the interaction between close-lying ²Σ and ²Π states of diatomic molecules. II. Λ-doubling of the ²Π levels, Mol. Phys., 1971, 21, 287. [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]

Notes

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Symbols used in this document:

EA Electron affinity

Δ_rG° Free energy of reaction at standard conditions

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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EA	Electron affinity
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions