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Chemical data page
This page provides supplementary chemical data on
ammonia .
Structure and properties
Thermodynamic properties
Phase diagram and crystalline states of ammonia I. cubic, II. hcp, III. fcc, IV. orthorhombic
Phase behavior
Triple point
195.4 K (−77.75 °C), 6.060 k
Pa
Critical point
405.5 K (132.3 °C), 11.300 M
Pa
Std enthalpy change of fusion , Δfus H o
+5.653 kJ/mol
Std entropy change of fusion , Δfus S o
+28.93 J/(mol·K)
Std enthalpy change of vaporization , Δvap H o
+23.35 kJ/mol at
BP of −33.4 °C
Std entropy change of vaporization , Δvap S o
+97.41 J/(mol·K) at
BP of −33.4 °C
Solid properties
Std enthalpy change of formation , Δf H o solid
? kJ/mol
Standard molar entropy ,S o solid
? J/(mol K)
Heat capacity , cp
? J/(mol K)
Liquid properties
Std enthalpy change of formation , Δf H o liquid
−80.882 ± 0.053 kJ/mol
[2]
Standard molar entropy ,S o liquid
? J/(mol K)
Heat capacity , cp
80.80 J/(mol K)
Gas properties
Std enthalpy change of formation , Δf H o gas
−45.556 ± 0.029 kJ/mol
[3]
Std
Gibbs free energy change of formation, Δf G o gas
−16.6 kJ/mol
Standard molar entropy ,S o gas
192.77 J/(mol K)
Heat capacity , cp
35.06 J/(mol K)
Heat capacity ratio , γ at 15 °C
1.310
van der Waals' constants
a = 422.5
L 2 k
Pa /
mol 2 b = 0.03707 L/mol
Vapor–liquid equilibrium data
P in mm Hg
1
10
40
100
400
760
1520
3800
7600
15600
30400
45600
T in °C
−109.1(s)
−91.9(s)
−79.2(s)
−68.4
−45.4
−33.6
−18.7
4.7
25.7
50.1
78.9
98.3
Table data (above) obtained from CRC Handbook of Chemistry and Physics 44th ed. The (s) notation indicates equilibrium temperature of vapor over solid. Otherwise temperature is equilibrium of vapor over liquid.
log10 of anydrous ammonia vapor pressure. Uses formula shown below.
Vapor-pressure formula for ammonia:
[4]
log10 P = A – B / (T − C ),
where P is pressure in k
Pa , and T is temperature in
kelvins ;
A = 6.67956, B = 1002.711, C = 25.215 for T = 190 K through 333 K.
Vapor over anhydrous ammonia
[5]
Temp.
Pressure
ρ of liquid
ρ of vapor
Δ vap H
−78 °C
5.90 k
Pa
−75 °C
7.93 kPa
0.73094 g/cm3
7.8241×10−5 g/cm3
−70 °C
10.92 kPa
0.72527 g/cm3
1.1141×10−4 g/cm3
−65 °C
15.61 kPa
0.71953 g/cm3
1.5552×10−4 g/cm3
−60 °C
21.90 kPa
0.71378 g/cm3
2.1321×10−4 g/cm3
−55 °C
30.16 kPa
0.70791 g/cm3
2.8596×10−4 g/cm3
−50 °C
40.87 kPa
0.70200 g/cm3
3.8158×10−4 g/cm3
1417 J/g
−45 °C
54.54 kPa
0.69604 g/cm3
4.9940×10−4 g/cm3
1404 J/g
−40 °C
71.77 kPa
0.68999 g/cm3
6.4508×10−4 g/cm3
1390 J/g
−35 °C
93.19 kPa
0.68385 g/cm3
8.2318×10−4 g/cm3
1375 J/g
−30 °C
119.6 kPa
0.67764 g/cm3
1.0386×10−3 g/cm3
1361 J/g
−25 °C
151.6 kPa
0.67137 g/cm3
1.2969×10−3 g/cm3
1345 J/g
−20 °C
190.2 kPa
0.66503 g/cm3
1.6039×10−3 g/cm3
1330 J/g
−15 °C
236.3 kPa
0.65854 g/cm3
1.9659×10−3 g/cm3
1314 J/g
−10 °C
290.8 kPa
0.65198 g/cm3
2.3874×10−3 g/cm3
1297 J/g
−5 °C
354.8 kPa
0.64533 g/cm3
2.8827×10−3 g/cm3
1280 J/g
0 °C
429.4 kPa
0.63857 g/cm3
3.4528×10−3 g/cm3
1263 J/g
5 °C
515.7 kPa
0.63167 g/cm3
4.1086×10−3 g/cm3
1245 J/g
10 °C
614.9 kPa
0.62469 g/cm3
4.8593×10−3 g/cm3
1226 J/g
15 °C
728.3 kPa
0.61755 g/cm3
5.7153×10−3 g/cm3
1207 J/g
20 °C
857.1 kPa
0.61028 g/cm3
6.6876×10−3 g/cm3
1187 J/g
25 °C
1003 kPa
0.60285 g/cm3
7.7882×10−3 g/cm3
1167 J/g
30 °C
1166 kPa
0.59524 g/cm3
9.0310×10−3 g/cm3
1146 J/g
35 °C
1350 kPa
0.58816 g/cm3
1.0431×10−2 g/cm3
1124 J/g
40 °C
1554 kPa
0.57948 g/cm3
1.2006×10−2 g/cm3
1101 J/g
45 °C
1781 kPa
0.57130 g/cm3
1.3775×10−2 g/cm3
1083 J/g
50 °C
2032 kPa
0.56287 g/cm3
1.5761×10−2 g/cm3
1052 J/g
55 °C
2310 kPa
0.55420 g/cm3
60 °C
2613 kPa
0.54523 g/cm3
2.05×10−2 g/cm3
65 °C
2947 kPa
0.53596 g/cm3
70 °C
3312 kPa
0.52632 g/cm3
2.65×10−2 g/cm3
75 °C
3711 kPa
0.51626 g/cm3
80 °C
4144 kPa
0.50571 g/cm3
3.41×10−2 g/cm3
85 °C
4614 kPa
0.49463 g/cm3
90 °C
5123 kPa
0.48290 g/cm3
4.39×10−2 g/cm3
95 °C
5672 kPa
0.47041 g/cm3
100 °C
6264 kPa
0.45693 g/cm3
5.68×10−2 g/cm3
Temp.
Pressure
ρ of liquid
ρ of vapor
Δ vap H
The table above gives properties of the
vapor–liquid equilibrium of anhydrous ammonia at various temperatures. The second column is vapor pressure in k
Pa . The third column is the density of the liquid phase. The fourth column is the density of the vapor. The fifth column is the heat of vaporization needed to convert one gram of liquid to vapor.
Freezing curve of ammonia-water system. Three eutectic points I. II. and III. are shown. Left of the I. point the frozen component is ice. Right of the III. point the frozen component is ammonia.
[6]
Vapor over aqueous ammonia solution
[7]
Temp.
%wt NH3
Partial pressure NH3
Partial pressure H2 O
0 °C
4.72
1.52 k
Pa
0.68 k
Pa
9.15
3.31 k
Pa
0.71 k
Pa
14.73
6.84 k
Pa
0.55 k
Pa
19.62
11.0 k
Pa
0.40 k
Pa
22.90
14.9 k
Pa
0.37 k
Pa
10 °C
4.16
2.20 k
Pa
1.21 k
Pa
8.26
4.96 k
Pa
1.17 k
Pa
12.32
8.56 k
Pa
1.01 k
Pa
15.88
12.68 k
Pa
0.93 k
Pa
20.54
19.89 k
Pa
0.83 k
Pa
21.83
22.64 k
Pa
0.73 k
Pa
19.9 °C
4.18
3.65 k
Pa
2.19 k
Pa
6.50
6.11 k
Pa
2.15 k
Pa
6.55
6.13 k
Pa
2.13 k
Pa
7.72
7.49 k
Pa
2.08 k
Pa
10.15
10.75 k
Pa
2.01 k
Pa
10.75
11.51 k
Pa
1.96 k
Pa
16.64
22.14 k
Pa
1.72 k
Pa
19.40
28.74 k
Pa
1.64 k
Pa
23.37
40.32 k
Pa
1.37 k
Pa
30.09 °C
3.93
5.49 k
Pa
4.15 k
Pa
7.43
11.51 k
Pa
3.89 k
Pa
9.75
16.00 k
Pa
3.80 k
Pa
12.77
23.33 k
Pa
3.55 k
Pa
17.76
38.69 k
Pa
3.31 k
Pa
17.84
38.81 k
Pa
3.24 k
Pa
21.47
53.94 k
Pa
2.95 k
Pa
40 °C
3.79
8.15 k
Pa
7.13 k
Pa
7.36
17.73 k
Pa
6.76 k
Pa
11.06
29.13 k
Pa
6.55 k
Pa
15.55
47.14 k
Pa
5.52 k
Pa
17.33
57.02 k
Pa
20.85
76.81 k
Pa
5.04 k
Pa
50 °C
3.29
10.54 k
Pa
11.95 k
Pa
5.90
20.17 k
Pa
11.61 k
Pa
8.91
32.88 k
Pa
11.07 k
Pa
11.57
45.56 k
Pa
10.75 k
Pa
14.15
60.18 k
Pa
10.27 k
Pa
14.94
64.94 k
Pa
10.03 k
Pa
60 °C
3.86
18.25 k
Pa
19.21 k
Pa
5.77
28.78 k
Pa
7.78
40.05 k
Pa
18.47 k
Pa
9.37
50.09 k
Pa
18.07 k
Pa
9.37
63.43 k
Pa
17.39 k
Pa
Temp.
%wt NH3
Partial Pressure NH3
Partial Pressure H2 O
Heat capacity of liquid and vapor
Heat capacity, cp , of anhydrous ammonia gas. Uses polynomial obtained from CHERIC.
[8]
Heat capacity of anhydrous liquid ammonia. Uses polynomial obtained from CHERIC.
[8]
Spectral data
Regulatory data
Safety data sheet
The handling of this chemical may incur notable safety precautions... It is highly recommend that you seek the Safety Data Sheet (
SDS ) for this chemical from a reliable source and follow its directions.
References
Linstrom, Peter J.; Mallard, William G. (eds.);
NIST Chemistry WebBook , NIST Standard Reference Database Number 69 , National Institute of Standards and Technology, Gaithersburg (MD)
External links