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Although we usually associate the boiling of water with the high temperatures of the stove (whether due to fire or electricity), the truth is that the boiling process also depends on atmospheric pressure and not only on the temperature of the water.
The boiling point is the limit at which temperature eliminates the ability of atmospheric pressure to keep water in a motionless or, say, bubble-free state. This can be seen when we compare the temperature needed to reach the boiling point in locations that are at sea level and locations that are in very high mountains.
In the mountains, water boils at lower temperatures, so the way you cook food must be adapted to achieve the same results as at sea level.
If we manage to eliminate the atmospheric pressure in a container with water, we will be able to observe how it reaches a boil without the need to use heat. This can be achieved with a vacuum machine that adapts to the container where the water is stored. However, there is an easier way to try this vacuum method at home.
How to boil water without heating it?
- – Use a syringe without a needle and fill the plunger with a little water. It is important that there is some air left.
- – Seal the bottom of the syringe to keep out more air.
- – Try to withdraw the plunger from the syringe as fast as you can, trying to observe the phenomenon in the water. You will be able to observe how it boils without having used any heat.
Withdrawing the plunger increases the space inside the syringe and the molecules spread out to fill the new space. The atmospheric pressure in the syringe drops and creates a partial vacuum that allows water molecules to easily pass from the liquid to the vapor phase.
The atmosphere, that layer of gases that surrounds the planet, exerts a pressure of about 1,003 grams per square centimeter, which translates to about 17,500 kilos on the head of each person. Fortunately, our internal pressure saves us from being crushed to death by atmospheric pressure. In addition, atmospheric pressure is what prevents the oceans and all bodies of water on the planet from evaporating.
References
- Fonseca, X. (2020). If the atmosphere weighs tons, why doesn’t it crush us? Available at: https://www.lavozdegalicia.es/noticia/sociedad/2020/05/04/atmosfera-pesa-toneladas-aplasta/00031588614188688368150.htm
- Rodriguez, J. (2013). Boiling of water without using heat… Fun Science . Available at: https://youtu.be/PId9EKVhVRw
- Iwater. Did you know that water does not always boil at 100ºC? Available at https://www.iagua.es/noticias/fundacion-aquae/sabias-que-agua-no-siempre-hierve-100oc-0 .
