This table provides the partial pressures in mmHg of nitric acid (HNO3) and water (H2O) over aqueous solutions of nitric acid at different concentrations and temperatures. The concentrations of the nitric acid solutions range from 20% to 100% by weight. The temperatures range from 0°C to 125°C. The table shows that as the concentration and temperature of the nitric acid solutions increase, the partial pressures of both HNO3 and H2O increase as well.

1. 2-88 PHYSICAL AND CHEMICAL DATA
TABLE 2-18 Partial Pressures of HNO3 and H2O over Aqueous Solutions of HNO3*
mmHg
Percentages are weight % HNO3 in solution.
20% 25% 30% 35% 40% 45% 50%
°C HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O
0 4.1 3.8 3.6 3.3 3.0 2.6 2.1
5 5.7 5.4 5.0 4.6 4.2 3.6 3.0
10 8.0 7.6 7.1 6.5 5.8 5.0 0.12 4.2
15 10.9 10.3 9.7 8.9 8.0 0.10 6.9 .18 5.8
20 15.2 14.2 13.2 12.0 10.8 .15 9.4 .27 7.9
25 20.6 19.2 17.8 16.2 0.12 14.6 .23 12.7 .39 10.7
30 27.6 25.7 23.8 0.09 21.7 .17 19.5 .33 16.9 .56 14.4
35 36.5 33.8 31.1 .13 28.3 .25 25.5 .48 22.3 .80 19.0
40 47.5 44 0.11 41 .20 37.7 .36 33.5 .68 29.3 1.13 25.0
45 62 0.09 57.5 .17 53 .28 48 .52 43 .96 38.0 1.57 32.5
50 80 .13 75 .25 69 .42 63 .75 56 1.35 49.5 2.18 42.5
55 0.09 100 .18 94 .35 87 .59 79 1.04 71 1.83 62.5 2.95 54
60 .13 128 .28 121 .51 113 .85 102 1.48 90 2.54 80 4.05 70
65 .19 162 .40 151 .71 140 1.18 127 2.05 114 3.47 100 5.46 88
70 .27 200 .54 187 1.00 174 1.63 159 2.80 143 4.65 126 7.25 110
75 .38 250 .77 234 1.38 217 2.26 198 3.80 178 6.20 158 9.6 138
80 .53 307 1.05 287 1.87 267 3.07 243 5.10 218 8.15 195 12.5 170
85 .74 378 1.44 352 2.53 325 4.15 297 6.83 268 10.7 240 16.3 211
90 1.01 458 1.95 426 3.38 393 5.50 359 9.0 325 13.7 292 20.9 258
95 1.37 555 2.62 517 4.53 478 7.32 436 11.7 394 17.8 355 26.8 315
100 1.87 675 3.50 628 6.05 580 9.7 530 15.5 480 23.0 430 34.2 383
105 2.50 800 4.65 745 7.90 690 12.7 631 20.0 573 29.2 520 43.0 463
110 16.5 755 25.7 688 37.0 625 54.5 560
115 32.5 810 46 740 67 665
120 84 785
55% 60% 65% 70% 80% 90% 100%
°C HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O HNO3 H2O HNO3
0 1.8 0.19 1.5 0.41 1.3 0.79 1.1 2 5.5 11
5 0.14 2.5 .28 2.1 .60 1.8 1.12 1.6 3 8 15
10 .21 3.5 .41 3.0 .86 2.6 1.58 2.2 4 1.2 11 22
15 .31 4.9 .59 4.1 1.21 3.5 2.18 3.0 6 1.7 15 30
20 .45 6.7 .84 5.6 1.68 4.9 3.00 4.1 8 2.4 20 42
25 .66 9.1 1.21 7.7 2.32 6.6 4.10 5.5 10.5 3.2 27 1 57
30 .93 12.2 1.66 10.3 3.17 8.8 5.50 7.4 14 4 36 1.3 77
35 1.30 16.1 2.28 13.6 4.26 11.6 7.30 9.8 18.5 5.5 47 1.8 102
40 1.82 21.3 3.10 18.1 5.70 15.5 9.65 12.8 24.5 7 62 2.4 133
45 2.50 28.0 4.20 23.7 7.55 20.0 12.6 16.7 32 9.5 80 3 170
50 3.41 36.3 5.68 31 10.0 26.0 16.5 21.8 41 12 103 4 215
55 4.54 46 7.45 39 12.8 33.0 21.0 27.3 52 15 127 5 262
60 6.15 60 9.9 51 16.8 43.0 27.1 35.3 67 20 157 6.5 320
65 8.18 76 13.0 64 21.7 54.5 34.5 44.5 85 25 192 8 385
70 10.7 95 16.8 81 27.5 68 43.3 56 106 31 232 10 460
75 13.9 120 21.8 102 35.0 86 54.5 70 130 38 282 13 540
80 18.0 148 27.5 126 43.5 106 67.5 86 158 48 338 16 625
85 23.0 182 34.8 156 54.5 131 83 107 192 60 405 20 720
90 29.4 223 43.7 192 67.5 160 103 130 230 73 480 24 820
95 37.3 272 55.0 233 83.5 195 125 158 278 89 570 29
100 47 331 69.5 285 103 238 152 192 330 108 675 35
105 58.5 400 84.5 345 124 288 183 231 392 129 790 42
110 73 485 103 417 152 345 221 278 465 155
115 90 575 126 495 181 410 262 330 545 185
120 110 685 156 590 218 490 312 393 640 219
125 187 700 260 580 372 469
*International Critical Tables, vol. 3, pp. 304–305.