1-Pentene
- Formula: C5H10
- Molecular weight: 70.1329
- IUPAC Standard InChIKey: YWAKXRMUMFPDSH-UHFFFAOYSA-N
- CAS Registry Number: 109-67-1
- 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: α-n-Amylene; Propylethylene; 1-C5H10; Pent-1-ene; 1-Pentene 95; Pentene-1
- 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:
Data at NIST subscription sites:
NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.
Gas phase thermochemistry data
Go To: Top, Phase change data, Gas phase ion energetics data, Mass spectrum (electron ionization), 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:
DRB - Donald R. Burgess, Jr.
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔfH°gas | -5. ± 2. | kcal/mol | AVG | N/A | Average of 6 values; Individual data points |
Constant pressure heat capacity of gas
Cp,gas (cal/mol*K) | Temperature (K) | Reference | Comment |
---|---|---|---|
19.68 | 200. | Thermodynamics Research Center, 1997 | p=1 bar. Recommended values were calculated from data for lower alkenes by a method of increments. These values are in good agreement with experimental data. The results of the similar estimation [ Kilpatrick J.E., 1946] are in poor agreement with experiment.; GT |
24.19 | 273.15 | ||
25.86 | 298.15 | ||
25.98 | 300. | ||
32.89 | 400. | ||
39.20 | 500. | ||
44.53 | 600. | ||
49.02 | 700. | ||
52.82 | 800. | ||
56.07 | 900. | ||
58.84 | 1000. | ||
61.28 | 1100. | ||
63.36 | 1200. | ||
65.20 | 1300. | ||
66.73 | 1400. | ||
68.21 | 1500. |
Constant pressure heat capacity of gas
Cp,gas (cal/mol*K) | Temperature (K) | Reference | Comment |
---|---|---|---|
26.850 ± 0.079 | 311.09 | Scott D.W., 1949 | GT |
30.151 ± 0.091 | 357.51 | ||
33.24 ± 0.10 | 402.32 | ||
35.47 ± 0.11 | 436.01 | ||
37.69 ± 0.11 | 471.08 |
Phase change data
Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), 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:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
DH - Eugene S. Domalski and Elizabeth D. Hearing
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
Tboil | 304. ± 8. | K | AVG | N/A | Average of 30 out of 31 values; Individual data points |
Quantity | Value | Units | Method | Reference | Comment |
Tfus | 107.75 | K | N/A | Streiff, Murphy, et al., 1946 | Uncertainty assigned by TRC = 0.2 K; TRC |
Tfus | 107.78 | K | N/A | Streiff, Murphy, et al., 1946 | Uncertainty assigned by TRC = 0.2 K; TRC |
Tfus | 107.88 | K | N/A | Streiff, Murphy, et al., 1946 | Uncertainty assigned by TRC = 0.1 K; TRC |
Quantity | Value | Units | Method | Reference | Comment |
Ttriple | 108.010 | K | N/A | Messerly, Todd, et al., 1990 | Crystal phase 1 phase; Uncertainty assigned by TRC = 0.003 K; TRC |
Ttriple | 107.790 | K | N/A | Messerly, Todd, et al., 1990 | Metastable crystal phase; Uncertainty assigned by TRC = 0.003 K; TRC |
Ttriple | 5.800 | K | N/A | Chao, Hall, et al., 1983 | Uncertainty assigned by TRC = 0.01 K; TRC |
Ttriple | 107.9 | K | N/A | Todd, Oliver, et al., 1947 | Uncertainty assigned by TRC = 0.5 K; this value not measured but taken from 1956-strmur 0; TRC |
Quantity | Value | Units | Method | Reference | Comment |
Tc | 464.8 ± 0.5 | K | N/A | Tsonopoulos and Ambrose, 1996 | |
Tc | 464.7 | K | N/A | Majer and Svoboda, 1985 | |
Tc | 465.1 | K | N/A | Wolfe, Kay, et al., 1983 | Uncertainty assigned by TRC = 0.3 K; $ %Y/SI 0.01 @Y/SI 0.3; TRC |
Tc | 463.77 | K | N/A | Mousa, Kay, et al., 1972 | Uncertainty assigned by TRC = 0.2 K; TRC |
Tc | 464.74 | K | N/A | Ambrose, Cox, et al., 1960 | Uncertainty assigned by TRC = 0.03 K; Visual, PRT, IPTS-48; TRC |
Quantity | Value | Units | Method | Reference | Comment |
Pc | 35.1 ± 0.5 | atm | N/A | Tsonopoulos and Ambrose, 1996 | |
Pc | 35.04 | atm | N/A | Wolfe, Kay, et al., 1983 | Uncertainty assigned by TRC = 0.20 atm; $ %Y/SI 1.5 @Y/SI 20.; TRC |
Pc | 35.046 | atm | N/A | Mousa, Kay, et al., 1972 | Uncertainty assigned by TRC = 0.0340 atm; TRC |
Quantity | Value | Units | Method | Reference | Comment |
Vc | 0.2984 | l/mol | N/A | Tsonopoulos and Ambrose, 1996 | |
Quantity | Value | Units | Method | Reference | Comment |
ρc | 3.35 ± 0.05 | mol/l | N/A | Tsonopoulos and Ambrose, 1996 | |
ρc | 3.32 | mol/l | N/A | Wolfe, Kay, et al., 1983 | Uncertainty assigned by TRC = 0.03 mol/l; TRC |
Quantity | Value | Units | Method | Reference | Comment |
ΔvapH° | 7.127 | kcal/mol | N/A | Majer and Svoboda, 1985 | |
ΔvapH° | 6.09 | kcal/mol | N/A | Reid, 1972 | AC |
ΔvapH° | 6.09 ± 0.02 | kcal/mol | C | Scott, Waddington, et al., 1949 | AC |
Enthalpy of vaporization
ΔvapH (kcal/mol) | Temperature (K) | Method | Reference | Comment |
---|---|---|---|---|
6.02 | 303.1 | N/A | Majer and Svoboda, 1985 | |
6.96 | 233. | A | Stephenson and Malanowski, 1987 | Based on data from 218. to 311. K.; AC |
6.38 | 295. | MM | Forziati, Camin, et al., 1950 | Based on data from 286. to 304. K.; AC |
6.43 | 288. | N/A | Scott, Waddington, et al., 1949 | Based on data from 273. to 334. K.; AC |
6.26 ± 0.02 | 284. | C | Scott, Waddington, et al., 1949 | AC |
6.02 ± 0.02 | 303. | C | Scott, Waddington, et al., 1949 | AC |
6.29 | 290. | N/A | Day, Nicholson, et al., 1948 | Based on data from 273. to 308. K.; AC |
6.14 | 341. | N/A | Day, Nicholson, et al., 1948 | Based on data from 313. to 368. K.; AC |
Enthalpy of vaporization
ΔvapH =
A exp(-βTr) (1 − Tr)β
ΔvapH =
Enthalpy of vaporization (at saturation pressure)
(kcal/mol)
Tr = reduced temperature (T / Tc)
View plot Requires a JavaScript / HTML 5 canvas capable browser.
Temperature (K) | A (kcal/mol) | β | Tc (K) | Reference | Comment |
---|---|---|---|---|---|
284. to 303. | 9.491 | 0.2663 | 464.7 | Majer and Svoboda, 1985 |
Antoine Equation Parameters
log10(P) = A − (B / (T + C))
P = vapor pressure (atm)
T = temperature (K)
View plot Requires a JavaScript / HTML 5 canvas capable browser.
Temperature (K) | A | B | C | Reference |
---|---|---|---|---|
285.98 to 303.87 | 3.90487 | 1014.294 | -43.367 | Forziati, Camin, et al., 1950, 2 |
Enthalpy of fusion
ΔfusH (kcal/mol) | Temperature (K) | Reference | Comment |
---|---|---|---|
1.41907 | 108.016 | Messerly, Todd, et al., 1990, 2 | DH |
1.40576 | 107.797 | Messerly, Todd, et al., 1990, 2 | c(metastable)/liq; DH |
1.388 | 107.90 | Chao, Hall, et al., 1983, 2 | DH |
1.388 | 107.9 | Todd, Oliver, et al., 1947, 2 | DH |
1.39 | 107.9 | Acree, 1991 | See also Messerly, Todd, et al., 1990, 2.; AC |
Entropy of fusion
ΔfusS (cal/mol*K) | Temperature (K) | Reference | Comment |
---|---|---|---|
13.14 | 108.016 | Messerly, Todd, et al., 1990, 2 | DH |
13.04 | 107.797 | Messerly, Todd, et al., 1990, 2 | c(metastable)/liq; DH |
12.86 | 107.90 | Chao, Hall, et al., 1983, 2 | DH |
12.86 | 107.9 | Todd, Oliver, et al., 1947, 2 | DH |
Temperature of phase transition
Ttrs (K) | Initial Phase | Final Phase | Reference | Comment |
---|---|---|---|---|
71.7 | crystaline | glass | Takeda, Oguni, et al., 1990 | DH |
Gas phase ion energetics data
Go To: Top, Gas phase thermochemistry data, Phase change data, Mass spectrum (electron ionization), References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data evaluated as indicated in comments:
L - Sharon G. Lias
Data compiled as indicated in comments:
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 C5H10+ (ion structure unspecified)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
IE (evaluated) | 9.49 ± 0.03 | eV | N/A | N/A | L |
Ionization energy determinations
IE (eV) | Method | Reference | Comment |
---|---|---|---|
9.50 | PI | Traeger, 1986 | LBLHLM |
9.52 ± 0.05 | EI | Holmes and Lossing, 1983 | LBLHLM |
9.42 ± 0.02 | PE | Ashmore and Burgess, 1978 | LLK |
9.52 ± 0.02 | PE | Bieri, Burger, et al., 1977 | LLK |
9.524 ± 0.003 | PE | Masclet, Grosjean, et al., 1973 | LLK |
9.48 | EI | Lossing, 1972 | LLK |
9.82 ± 0.06 | EI | Gross and Wilkins, 1971 | LLK |
9.50 ± 0.02 | PI | Watanabe, Nakayama, et al., 1962 | RDSH |
9.50 ± 0.02 | PI | Steiner, Giese, et al., 1961 | RDSH |
9.68 ± 0.01 | PE | Krause, Taylor, et al., 1978 | Vertical value; LLK |
9.54 ± 0.02 | PE | Bunzli, Burak, et al., 1973 | Vertical value; LLK |
Appearance energy determinations
Ion | AE (eV) | Other Products | Method | Reference | Comment |
---|---|---|---|---|---|
C3H6+ | 10.68 ± 0.02 | C2H4 | PI | Brand and Baer, 1984 | LBLHLM |
C3H6+ | 11.61 ± 0.08 | C2H4 | EI | Gross and Wilkins, 1971 | LLK |
C4H7+ | 10.50 | CH3 | PI | Traeger, 1986 | LBLHLM |
C4H7+ | 10.64 | CH3 | EI | Brand and Baer, 1984 | LBLHLM |
C4H7+ | 10.63 ± 0.02 | CH3 | PI | Brand and Baer, 1984 | LBLHLM |
C4H7+ | 10.64 | CH3 | EI | Lossing, 1972 | LLK |
C4H7+ | 11.35 ± 0.07 | CH3 | EI | Gross and Wilkins, 1971 | LLK |
Mass spectrum (electron ionization)
Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics 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: NIST Mass Spectrometry Data Center, William E. Wallace, director
Spectrum
Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.
Additional Data
View image of digitized spectrum (can be printed in landscape orientation).
Due to licensing restrictions, this spectrum cannot be downloaded.
Owner | NIST Mass Spectrometry Data Center Collection (C) 2014 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. |
---|---|
Origin | Japan AIST/NIMC Database- Spectrum MS-NW-2716 |
NIST MS number | 230821 |
References
Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Mass spectrum (electron ionization), Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Thermodynamics Research Center, 1997
Thermodynamics Research Center,
Selected Values of Properties of Chemical Compounds., Thermodynamics Research Center, Texas A&M University, College Station, Texas, 1997. [all data]
Kilpatrick J.E., 1946
Kilpatrick J.E.,
Heats, equilibrium constants, and free energies of formation of the monoolefin hydrocarbons,
J. Res. Nat. Bur. Stand, 1946, 36, 559-612. [all data]
Scott D.W., 1949
Scott D.W.,
Thermodynamic properties of three isomeric pentenes,
J. Am. Chem. Soc., 1949, 71, 2767-2773. [all data]
Streiff, Murphy, et al., 1946
Streiff, A.J.; Murphy, E.T.; Sedlak, V.A.; Willingham, C.B.; Rossini, F.D.,
Purification, Purity, and Freezing Points of 7 Heptanes, 16 Octanes, 6 Pentene, Cyclopentene, and 7 C9H12 Alkylbenzenes of the API-Standard and API-NBS Series,
J. Res. Natl. Bur. Stand. (U. S.), 1946, 37, 331. [all data]
Messerly, Todd, et al., 1990
Messerly, J.F.; Todd, S.S.; Finke, H.L.; Lee-Bechtold, S.H.; Guthrie, G.B.; Steele, W.V.; Chirico, R.D.,
Heat capacities of pent-1-ene (10 K to 320 K), cis-hex-2-ene (10 K to 330 K), non-1-ene (10 K to 400 K) and hexadec-1-ene (10 K to 400 K),
J. Chem. Thermodyn., 1990, 22, 1107-28. [all data]
Chao, Hall, et al., 1983
Chao, J.; Hall, K.R.; Yao, J.M.,
Thermodynamic Properties of Simple Alkenes,
Thermochim. Acta, 1983, 64, 285. [all data]
Todd, Oliver, et al., 1947
Todd, S.S.; Oliver, G.D.; Huffman, H.M.,
The heat capacities, heats of fusion and entropies of the six pentenes.,
J. Am. Chem. Soc., 1947, 69, 1519. [all data]
Tsonopoulos and Ambrose, 1996
Tsonopoulos, C.; Ambrose, D.,
Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons,
J. Chem. Eng. Data, 1996, 41, 645-656. [all data]
Majer and Svoboda, 1985
Majer, V.; Svoboda, V.,
Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation, Blackwell Scientific Publications, Oxford, 1985, 300. [all data]
Wolfe, Kay, et al., 1983
Wolfe, D.; Kay, W.B.; Teja, A.S.,
Phase Equilibria in the n-Pentane + Pent-1-ene System 1. Critical States,
J. Chem. Eng. Data, 1983, 28, 319. [all data]
Mousa, Kay, et al., 1972
Mousa, A.H.N.; Kay, W.B.; Kreglewski, A.,
The critical constants of binary mixtures of certain perfluoro-compounds with alkanes,
J. Chem. Thermodyn., 1972, 4, 301-11. [all data]
Ambrose, Cox, et al., 1960
Ambrose, D.; Cox, J.D.; Townsend, R.,
The critical temperatures of forty organic compounds,
Trans. Faraday Soc., 1960, 56, 1452. [all data]
Reid, 1972
Reid, Robert C.,
Handbook on vapor pressure and heats of vaporization of hydrocarbons and related compounds, R. C. Wilhort and B. J. Zwolinski, Texas A Research Foundation. College Station, Texas(1971). 329 pages.$10.00,
AIChE J., 1972, 18, 6, 1278-1278, https://doi.org/10.1002/aic.690180637
. [all data]
Scott, Waddington, et al., 1949
Scott, D.W.; Waddington, G.; Smith, J.C.; Huffman, H.M.,
Thermodynamic properties of three isomeric pentenes,
J. Am. Chem. Soc., 1949, 71, 2767-2773. [all data]
Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw,
Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2
. [all data]
Forziati, Camin, et al., 1950
Forziati, A.F.; Camin, D.L.; Rossini, F.D.,
Density, refractive index, boiling point, and vapor pressure of eight monoolefin (1-alkene), six pentadiene, and two cyclomonoolefin hydrocarbons,
J. RES. NATL. BUR. STAN., 1950, 45, 5, 406, https://doi.org/10.6028/jres.045.044
. [all data]
Day, Nicholson, et al., 1948
Day, H.O.; Nicholson, D.E.; Felsing, W.A.,
The Vapor Pressures and Some Related Quantities of Pentene-1 from 0 to 200°,
J. Am. Chem. Soc., 1948, 70, 5, 1784-1785, https://doi.org/10.1021/ja01185a037
. [all data]
Forziati, Camin, et al., 1950, 2
Forziati, a.F.; Camin, D.L.; Rossini, F.D.,
Density, refractive index, boiling point, and vapor pressure of eight monoolefin (1-alkene), six pentadiene, and two cyclomonoolefin hydrocarbons,
J. Res. NBS, 1950, 45, 406-410. [all data]
Messerly, Todd, et al., 1990, 2
Messerly, J.F.; Todd, S.S.; Finke, H.L.; Lee-Bechtold, S.H.; Guthrie, G.B.; Steele, W.V.; Chirico, R.D.,
Heat capacities of pent-1-ene (10K to 320K), cis-hex-2-ene (10K to 330K), non-1-ene (10K to 400K), and hexadec-1-ene (10K to 400K),
J. Chem. Thermodynam., 1990, 22, 1107-1128. [all data]
Chao, Hall, et al., 1983, 2
Chao, J.; Hall, K.R.; Yao, J.M.,
Thermodynamic properties of simple alkenes,
Thermochim. Acta, 1983, 64(3), 285-303. [all data]
Todd, Oliver, et al., 1947, 2
Todd, S.S.; Oliver, G.D.; Huffman, H.M.,
The heat capacities, heats of fusion and entropies of the six pentenes,
J. Am. Chem. Soc., 1947, 69, 1519-1525. [all data]
Acree, 1991
Acree, William E.,
Thermodynamic properties of organic compounds: enthalpy of fusion and melting point temperature compilation,
Thermochimica Acta, 1991, 189, 1, 37-56, https://doi.org/10.1016/0040-6031(91)87098-H
. [all data]
Takeda, Oguni, et al., 1990
Takeda, K.; Oguni, M.; Suga, H.,
A DTA apparatus for vapour-deposited samples. Characterisation of some vapour-deposited hydrocarbons,
Thermochim. Acta, 1990, 158(1), 195-203. [all data]
Traeger, 1986
Traeger, J.C.,
Heat of formation for the 1-methylallyl cation by photoionization mass spectrometry,
J. Phys. Chem., 1986, 90, 4114. [all data]
Holmes and Lossing, 1983
Holmes, J.L.; Lossing, F.P.,
The need for adequate thermochemical data for the interpretation of fragmentation mechanisms and ion structure assignments,
Int. J. Mass Spectrom. Ion Phys., 1983, 47, 133. [all data]
Ashmore and Burgess, 1978
Ashmore, F.S.; Burgess, A.R.,
Photoelectron spectra of the unbranched C5-C7 alkenes, aldehydes and ketones,
J. Chem. Soc. Faraday Trans. 2, 1978, 74, 734. [all data]
Bieri, Burger, et al., 1977
Bieri, G.; Burger, F.; Heilbronner, E.; Maier, J.P.,
Valence ionization enrgies of hydrocarbons,
Helv. Chim. Acta, 1977, 60, 2213. [all data]
Masclet, Grosjean, et al., 1973
Masclet, P.; Grosjean, D.; Mouvier, G.,
Alkene ionization potentials. Part I. Quantitative determination of alkyl group structural effects,
J. Electron Spectrosc. Relat. Phenom., 1973, 2, 225. [all data]
Lossing, 1972
Lossing, F.P.,
Free radicals by mass spectrometry. XLV. Ionization potentials and heats of formation of C3H3, C3H5, and C4H7 radicals and ions,
Can. J. Chem., 1972, 50, 3973. [all data]
Gross and Wilkins, 1971
Gross, M.L.; Wilkins, C.L.,
Computer-assisted ion cyclotron resonance appearance potential measurements for C5H10 isomers,
Anal. Chem., 1971, 43, 1624. [all data]
Watanabe, Nakayama, et al., 1962
Watanabe, K.; Nakayama, T.; Mottl, J.,
Ionization potentials of some molecules,
J. Quant. Spectry. Radiative Transfer, 1962, 2, 369. [all data]
Steiner, Giese, et al., 1961
Steiner, B.; Giese, C.F.; Inghram, M.G.,
Photoionization of alkanes. Dissociation of excited molecular ions,
J. Chem. Phys., 1961, 34, 189. [all data]
Krause, Taylor, et al., 1978
Krause, D.A.; Taylor, J.W.; Fenske, R.F.,
An analysis of the effects of alkyl substituents on the ionization potentials of n-alkenes,
J. Am. Chem. Soc., 1978, 100, 718. [all data]
Bunzli, Burak, et al., 1973
Bunzli, J.C.; Burak, A.J.; Frost, D.C.,
Through-space interaction in non-conjugated acyclic dienes studied by photoelectron spectroscopy,
Tetrahedron, 1973, 29, 3735. [all data]
Brand and Baer, 1984
Brand, W.A.; Baer, T.,
Dissociation dynamics of energy-selected C5H10+ ions,
J. Am. Chem. Soc., 1984, 106, 3154. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Mass spectrum (electron ionization), References
- Symbols used in this document:
AE Appearance energy Cp,gas Constant pressure heat capacity of gas IE (evaluated) Recommended ionization energy Pc Critical pressure Tboil Boiling point Tc Critical temperature Tfus Fusion (melting) point Ttriple Triple point temperature Ttrs Temperature of phase transition Vc Critical volume ΔfH°gas Enthalpy of formation of gas at standard conditions ΔfusH Enthalpy of fusion ΔfusS Entropy of fusion ΔvapH Enthalpy of vaporization ΔvapH° Enthalpy of vaporization at standard conditions ρc Critical density - 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.