You can make liquid nitrogen bubbles by adding liquid nitrogen to warm soapy water.
Making bubbles with liquid nitrogen is a fascinating demonstration of cryogenics and gas expansion. It's a process driven by the extreme temperature difference between the liquid nitrogen and the surrounding water.
The Simple Process
The method is straightforward and relies on basic physics principles:
Steps to Create Liquid Nitrogen Bubbles
Here is the fundamental process:
- Prepare Soapy Water: Start with a container of warm water.
- Add Soap: Mix in some liquid dish soap to create a solution that can hold bubbles. The soap lowers the surface tension of the water, allowing bubbles to form and stabilize.
- Introduce Liquid Nitrogen: Carefully add liquid nitrogen into the warm soapy water.
Understanding the Reaction
When the liquid nitrogen is added to warm soapy water, it begins to boil very quickly. Liquid nitrogen is extremely cold (around -196°C or -320°F), and the warm water transfers heat to it rapidly. This rapid heating causes the liquid nitrogen to undergo a phase change directly from liquid to gas – a process called boiling.
With all this gas being created, it forms bubbles in the soapy water. The soap allows the water to form films that trap the expanding nitrogen gas. Since it is nitrogen gas being created from the liquid nitrogen boiling, it is nitrogen gas that is inside the bubbles. These bubbles behave much like regular soap bubbles but are filled with very cold nitrogen gas and often exhibit unique properties due to the temperature.
Why Does This Happen?
- Boiling Point: Nitrogen's boiling point is far below the temperature of even cold water. Warm water significantly accelerates this boiling process.
- Gas Expansion: As nitrogen boils into a gas, its volume expands dramatically. One liter of liquid nitrogen turns into about 700 liters of nitrogen gas at room temperature. This rapid expansion forces its way through the soapy water.
- Soap's Role: The soap molecules help to stabilize the thin film of water around the expanding gas pockets, allowing bubbles to form rather than just having the gas escape as a turbulent vapor.
This simple interaction between the ultra-cold liquid and the warmer, soapy liquid is the key to creating these unique bubbles.
