Door 13: The less pressure, the lower the boiling point

Inge and Magne show how you can easily make water boil at a low temperature by lowering the air pressure.

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Look carefully at the water inside the syringe, it starts to boil!

The boiling point of water depends on the air pressure. In a normal air pressure at sea level (1,013 bar), the boiling point of water is 100 degrees Celsius. The air pressure decreases with height, so that at Galdhøpiggen the boiling point of the water is approx. 92 degrees Celsius, on Mount Everest approx. 73 degrees. We will show how you can make water boil at an even lower temperature, in fact all the way down to almost 40 degrees.

You need:

  • A 50 ml syringe (or something similar that you can change the volume in)
  • Hot water

Recipe:

  1. Fill hot water in a cup (ours was 64 degrees Celcius)
  2. Soak 15-20 ml of warm water in the syringe
  3. Hold your finger in front of the opening of the syringe
  4. Pull out the plunger, as the air pressure inside the syringe drops. Look carefully at the water inside the syringe, it starts to boil!