Boiling Point
Steam is produced when water is heated to its boiling point.
The boiling point is the temperature at which a liquid boils and becomes vapour, it is also referred to as the saturation temperature.
At sea level, water boils at 212°F (100°C). If the pressure surrounding the water decreases, the temperature required to boil the water will also decrease. If the pressure surrounding the water increases, the temperature required to boil the water will also increase.
The boiling point of a liquid increases as pressure increases and decreases as pressure decreases.
The below table shows the boiling point of water at various pressures. Note that the temperature required to boil water gradually increases as the pressure increases.
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Water Boiling Point |
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Imperial Units |
Metric Units |
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Pressure (psia) |
Temperature |
Pressure |
Temperature |
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14.7 |
212 |
1.0 |
100 |
|
30.0 |
250 |
2.1 |
121 |
|
45.0 |
275 |
3.1 |
135 |
|
60 |
293 |
145 |
4.1 |
Water Boiling Point Table
Boiling water in an open vessel requires a large amount of energy because it is inefficient. However, if the vessel is fully enclosed with an outlet for steam and inlet for water, the amount of energy required to boil water reduces dramatically.
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i |
Home Experiment: Measure the time it takes to boil a certain amount of water in a pot with the lid off, then repeat the experiment with the lid on. The time needed to boil the water with the lid on will be far less than with the lid-off. |
Additional Resources
https://en.wikipedia.org/wiki/Boiling_point
https://www.britannica.com/science/boiling-point
https://www.chem.purdue.edu/gchelp/liquids/boil.html
https://www.westfield.ma.edu/PersonalPages/cmasi/gen_chem2/colligative/freezing_boiling.htm