Saturated Vapor Pressure, Density for Water

-10
14
2.15
2.36
37
98.6
47.07
44
0
32
4.58
4.85
40
104
55.3
51.1
5
41
6.54
6.8
60
140
149.4
130.5
10
50
9.21
9.4
80
176
355.1
293.8
11
51.8
9.84
10.01
95
203
634
505
12
53.6
10.52
10.66
96
205
658
523
13
55.4
11.23
11.35
97
207
682
541
14
57.2
11.99
12.07
98
208
707
560
15
59
12.79
12.83
99
210
733
579
20
68
17.54
17.3
100
212
760
598
25
77
23.76
23
101
214
788
618
30
86
31.8
30.4
200
392
11659
7840
Graph for waterSaturated vapor pressure
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Saturated Vapor Pressure for Water

Saturation vapor pressureTable for waterVapor density graph
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Saturated Vapor Density for Water

Saturation vapor pressureTable for waterVapor pressure graph
Empirical fit of vapor density vs temperature
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Boiling Point

The boiling point is defined as the temperature at which the saturated vapor pressure of a liquid is equal to the surrounding atmospheric pressure. For water, the vapor pressure reaches the standard sea level atmospheric pressure of 760 mmHg at 100C. Since the vapor pressure increases with temperature, it follows that for pressure greater than 760 mmHg (e.g., in a pressure cooker), the boiling point is above 100C and for pressure less than 760 mmHg (e.g., at altitudes above sea level), the boiling point will be lower than 100C. As long as a vessel of water is boiling at 760 mmHg, it will remain at 100C until the phase change is complete. Rapidly boiling water is not at a higher temperature than slowly boiling water. The stability of the boiling point makes it a convenient calibration temperature for temperature scales.

At the boiling point,
saturated vapor pressure
equals atmospheric pressure.

Boiling and evaporationBoiling point variation with pressure
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Boiling Point Variation

The standard boiling point for water at 100íC is for standard atmospheric pressure, 760 mmHg. It is the experience of high altitude hikers that it takes longer to cook food at altitude because the boiling point of water is lower. On the other hand, food cooks more quickly in a pressure cooker because the boiling point is elevated. Raising or lowering the pressure by about 28 mmHg will change the boiling point by 1íC. Although the vapor pressure variation with temperature is a non-linear one, the boiling point variation can be approximated near 100íC by an empirical fit of the available data. This can provide the following estimate of the boiling point: For a pressure of mmHg, the boiling point will be approximately íC. For variations in atmospheric pressure with altitude according to the barometric formula, the boiling point at a height of m = ft above sea level (atmos. pressure mmHg) would be approximately íC.

Barometric formula
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Boiling Point Variation Near 100 C


Values were taken from the saturated vapor pressure table for water near 100 degrees C. An empirical fit to these data values was made, and the formula obtained is shown on the diagram. It could be considered to be reasonably valid only for a few degrees above and below 100 degrees C since the curve is very non-linear.

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