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 water

Saturated vapor pressure

Saturated Vapor Pressure for Water

Saturation vapor pressure

Table for water

Vapor density graph

Saturated Vapor Density for Water

Saturation vapor pressure

Table for water

Vapor pressure graph

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 evaporation

Boiling point variation with pressure

Boiling Point Variation

The standard boiling point for water at 100¡C 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 1¡C. Although the vapor pressure variation with temperature is a non-linear one, the boiling point variation can be approximated near 100¡C 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 ¡C. 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 ¡C.

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.