Anhydrous Hydrogen Fluoride
and Hydrofluoric Acid
Physical Properties
Solvay
Special Chemicals
2
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Solvay Special Chemicals
Introduction
Hydrogen Fluoride
Hydrogen fluoride (HF) is manufactured by Solvay in Bad Wimpfen
(Germany), Ciudad Juárez (Mexico), Quzhou (Lansol JV in China) and Porto
Marghera (Italy). Besides calcium fluoride (CaF2), also known as fluorspar,
which Solvay sources in part from its own mines in places such as Okorusu
(Namibia) and Chiprovtsi (Bulgaria), sulfuric acid and oleum are also used
as raw materials. In a rotary kiln the mixture of calcium fluoride and sulfuric acid/oleum is heated, forming hydrogen fluoride and calcium sulfate
(CaSO4). The gaseous hydrogen fluoride then has to undergo several purification steps to obtain technical grade HF (approx. 99.9%). The CaSO4
(anhydrite) thus produced is used in the building materials industry and
has further applications in screed mixtures. The stored technical-grade HF
is used for the production of fluorine-containing materials, or is dissolved
in water to obtain hydrofluoric acid. Hydrofluoric acid can also be further
purified for use in the semiconductor industry.
Most of the anhydrous hydrogen fluoride (AHF) is used in the production
of fluorinated carbon compounds, the so-called HCFCs and HFCs. These
materials are essential coolants, foam blowing agents, fire-extinguishing
agents, solvents and raw materials for the production of fluorinated monomers for the plastics industry. Some additional major uses of AHF in organic chemistry are in Balz-Schiemann reactions, alkylation reactions in the
petrochemical industry, reactions with SF4 in AHF to produce CF3 or CF2H
functional groups, and electrofluorination reactions.
Anhydrous hydrogen fluoride is highly soluble in water. The resulting
hydrofluoric acid is transported in drums, tank trucks and rubber-lined railway tank cars. Hydrofluoric acid is used to clean casst metal, copper and
brass. It removes efflorescence from bricks, stones and sand particles from
metal castings. Frosted products, such as electric light bulbs, and
other etched glass, e.g. polished crystal glass, and enamels are well-known.
Purified e-grade hydrofluoric acid is required particularly for etching silicon in the photovoltaic and semiconductor industries. The manufacture of
metal fluorides by fluoride precipitation reactions between HF and metal
oxides, hydroxides or carbonates is of major importance for Solvay Fluor.
Cover photo:
Solvay Special Chemicals Mexico S.A. de C.V. Plant in Ciudad Juárez, Mexico
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Contents
Solvay Special Chemicals
Physical properties of anhydrous hydrogen fluoride.................................. 4
Physical properties of aqueous 70% and 50% hydrogen fluoride............. 5
The boiling point and liquid-vapor composition
of the system HF-H2O.............................................................................. 6
Vapor – liquid equilibrium diagram at the normal boiling point................. 6
Freezing points of aqueous hydrogen fluoride solutions........................... 7
Density of aqueous hydrogen fluoride...................................................... 7
Partial pressure of hydrogen fluoride over HF-H2O solution...................... 8
Partial pressure of water over HF-H2O solution......................................... 8
Heat of dilution of aqueous hydrogen fluoride solutions........................... 9
Specific conductivity of aqueous hydrogen fluoride solutions................... 9
Heat capacity of anhydrous hydrogen fluoride........................................ 10
Heat capacity functions of aqueous hydrogen
fluoride solutions................................................................................... 10
Viscosity of hydrogen fluoride.................................................................11
Bibliography............................................................................................11
Contact . ............................................................................................. 12
3
4
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Solvay Special Chemicals
Physical Properties of
anhydrous hydrogen
fluoride
Formula weight (calculated) a)
20.006
Molecular Weight
Saturated vapor, at boiling point a)
Saturated vapor, at 100 °C a)
78.24
49.08
Boiling point at 1,013 mbar [°C] a)
19.51
Melting point [°C] a)
– 83.37
Density
Liquid, at 25 °C [kg/m3] a)
Vapor, saturated, at 25 °C [kg/m3] a)
957.6
3.553
Gas density, at 1bar and 25 °C [kg/m3] b)
0.83
Specific volume at 1,013 bar and 21 °C [m3/kg] b)
1.205
Vapor pressure, at 25°C [bar] a)
1.23
Heat of vaporization
Boiling point, at 1,013 mbar [kJ/kg] a)
374.5
Heat of fusion, melting point [kJ/kg] a)
196.9
Heat capacity, constant pressure
Liquid, boiling point [kJ/kg] a)
Vapor, at 25 °C, 1,013 mbar [kJ/kg. K] a)
2.32
1.46
Heat of formation, Ideal gas, at 25 °C [kJ/mol] a)
–272
Free energy of formation, Ideal gas, at 25 °C [kJ/mol] a)
–272
Heat capacity at constant pressure (cP)
1,013 bar and 25 °C [kJ/(mol·K)] b)
0.029
Entropy, ideal gas, at 25 °C [J/mol K] a)
174
Critical temperature [°C] a)
188
Critical pressure [bar] a)
64.9
Critical density [kg/m3] a)
290
Viscosity of liquid, at 0 °C [cP] a)
0.26
Surface tension, at boiling point, dyn/cm a)
8.6
Refractive index, 5,893 Å at 25 °C a)
1.1574
Molar refractivity, 5,893 Å, formula wt. [cm3] a)
2.13
Conductivity at 0 °C [µS / cm] a)
<1.6
Dielectric constant, at 0 °C a)
83.6
Dipole moment [D] a)
1.83
Compressibility Factor at 1,013 bar and 15 °C b) [Z]
0.9835
Thermal conductivity at 1,013 bar and 0 °C [mW/(m·K)] b)
23.53
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Physical properties of
aqueous 50% and
70% hydrogen fluoride
at 20 °C
Solvay Special Chemicals
50 wt %
HF
70 wt %
HF
1.17
1.23
Partial pressure HF [mbar]
over HF-H2O solution a)
16.53
157.33
Partial pressure H2O [mbar]
over HF-H2O solution a)
3.97
0.13
1g HF diluted with H2O
Heat of dillution to < 1 wt % HF [J] a)
234
456
Freezing point [°C] d)
– 35
– 86
Boiling point [°C] a)
105
66
Density liquid [kg/l] a)
5
The boiling point and
liquid –vapor composition
of the system HF – H2O c)
120
248
110
230
100
212
90
194
80
176
70
158
60
140
50
122
40
104
30
86
Vapor
Liquid
20
68
10
50
0
32
0
10
20
30
40
50
60
70
80
90
100
Vapor – liquid
equilibrium diagram at
the normal boiling point c)
Concentration HF vapor [wt%]
HF Concentration [wt.%]
100
90
80
70
60
50
40
Vapor
30
Liquid
20
10
0
20
40
60
80
HF Concentration [wt.%]
Temperature [°F]
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Solvay Special Chemicals
Temperature [°C]
6
Freezing point of
aqueous solutions of
hydrogen fluoride d)
Solvay Special Chemicals
Temperature [°K]
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
270
H2O HF
250
230
210
H2O 2HF
190
H2O 4HF
170
150
0
10
20
30
40
50
60
70
80
90
100
1.25
78
1.15
72
1.05
66
0.95
59
0°C
20°C
40°C
60°C
0.85
53
47
0.75
0
10
20
30
40
50
60
70
80
90
100
HF Concentration [wt.%]
Density [b/ft3]
Density of aqueous
hydrogen fluoride a)
Density [g/cm3]
HF Concentration [mole%]
7
Partial pressure of
hydrogen fluoride over
HF – H2O solution a)
174
12,000
100°C
80°C
60°C
40°C
20°C
0°C
10,000
8,000
145
116
6,000
87
4,000
58
2,000
29
0
0
10
20
30
40
50
60
70
80
90
Partial p ressure [psi]
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Solvay Special Chemicals
Partial pressure [mbar]
8
0
100
17
1,200
100°C
80°C
60°C
40°C
20°C
1,000
800
15
12
600
9
400
6
200
3
0
0
10
20
30
40
50
60
70
80
90
0
100
HF Concentration [wt.%]
Partial pressure [psi]
Partial pressure of H2O
over HF – H2O solution a)
Partial pressure [mbar]
HF Concentration [wt.%]
1,000
0.95
900
0.85
800
0.76
700
0.66
600
0.57
500
0.47
400
0.38
300
0.28
200
0.19
100
0.09
0
0
10
20
30
40
50
60
70
80
90
0
100
Specific conductivity
of HF-H2O solutions,
at 0 °C a)
Conductivity [µS/cm]
HF Concentration [wt.%]
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
70
75
80
85
90
95
100
HF Concentration [wt%]
9
Heat evolved when 1 gram HF is diluted with H2O [Btu]
Heat of dilution of
aqueous HF solutions a)
Solvay Special Chemicals
Heat evolved when 1 gram HF is diluted with H2O [J]
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
Solvay Special Chemicals
Heat capacity of
anhydrous hydrogen
fluoride e)
Cp [kJ/kg K]
10
3.0
Melting point 189,79°K
2.5
2.0
1.5
1.0
0.5
0
0
100
50
150
200
250
300
Heat capacity function
for aqueous hydrogen
fluoride at 25 °C f)
Heat Capacity [kJ/kg K]
Temperature [°K]
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
60
70
HF Concentration [wt.%]
68
20
Pure HF
Commercial HF
10
50
0
32
–10
14
–20
–4
–30
–22
– 40
–40
–50
–58
– 60
–76
–70
0E+00
2E-07
4E-07
6E-07
8E-07
11
Temperature [°F]
Viscosity of hydrogen
fluoride with differences
in purity g)
Solvay Special Chemicals
Temperature [°C]
Anhydrous Hydrogen Fluoride and Hydrofluoric Acid
–94
1E-06
Viskosity [m2/s]
Bibliography
a) Kirk-Othmer, E. of Chem. Techn., 2nd Edition Volume 9,
610- 625 (1966)
b)Air Liquide Gas Encyclopaedia “Hydrogen Fluoride” (1976)
c) P.A. Munter, O.T. Aepeli and R.A. Kossatz, Ind. Eng. Chem. 39,
427 - 431 (1947)
d)G.H. Cady and J.H. Hildebrand, J. Am. Chem. Soc. 52, 3843-3846 (1930)
e) Jih-Heng Hu, David White, H. L. Johnston, J. Am. Chem. Soc., 75 (5),
1232–1236 (1953)
f) Kelly L. Elmore, John D. Hatfield, Charles M. Mason, Arthur D. Jones,
J. Am. Chem. Soc., 71 (8), pp 2710–2714 (1949)
g) J. H. Simons, Richard D. Dresdner, J. Am. Chem. Soc., 66 (7),
pp 1070–1072 (1944)
In addition to physical properties data, Solvay Fluorides, LLC is pleased to offer supporting documentation and reference literature including, but not limited to:
n First Aid and Medical Treatment for Hydrofluoric Acid Exposure tri-fold poster
n Summary of First Aid Procedures for Hydrofluoric Acid Exposure wallet cards
n Making it Safe for Hydrofluoric Acid safety training video
n Making it Safe for Hydrofluoric Acid Drum Handling safety training video
n Making it safe for Anhydrous Hydrofluoric Acid safety training video
(available late 2011)
n Summary of First Aid Procedures for Hydrofluoric Acid Exposure wall poster
(available late 2011)
For a full range of recommended practices specific to the Hydrogen Fluoride (HF)
Industry including bulk storage guidelines, materials of construction, personal protective equipment and unloading guidelines, please visit the Hydrogen Fluoride Industry
Practices Institute website at:
www.HFIPI.com
For all other information, please visit our website at:
www.solvay-fluor.com
For technical or sales information please refer to
Solvay Fluor GmbH
Solvay Fluorides, LLC
Solvay Fluor Korea CO., LTD
Postfach 220
30002 Hannover
Germany
3333 Richmond Avenue
Houston, Texas 77098
USA
5th Fl. Donghwa Bldg. 58-7
Seosomun-Dong, Jung-Gu
Seoul, 100-736, Korea
Phone +49 511 857-2444
Fax +49 511 857-2178
Phone+1 713 525-6566
Fax +1 713 525-7805
Phone+82 2 757 5353
Fax +82 2 756 0354
www.solvay-fluor.com
www.solvaychemicals.us
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All statements, information, and data given herein are believed to be accurate and reliable but are presented without
guarantee, warranty or responsibility of any kind, express or implied, including without warranty of merchantability or
fitness of use. Statements or suggestions concerning possible use of our products are made without representation or
warranty that any such use is free of patent infringement, and are not recommendations to infringe any patent. The user
should not assume that all safety measures are indicated, or that other measures may not be required. In any case, the
user is not exempt from observing all legal, administrative and regulatory procedures relating to the product, personal
hygiene, and protection of human welfare and the environment. The information provided hereunder is for information
purposes only, and neither Solvay Fluor GmbH nor its affiliates accepts any liability in connection with its use. This information is for use by technically skilled persons at their own discretion and risk and does not relate to the use of any product in combination with any other substance or any other process. Solvay Fluor GmbH and its affiliates reserve the right to
make additions, deletions, or modifications to the information at any time without prior notification.
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