Liquid Nitrogen in Hot Water

When liquid nitrogen is poured into a beaker of hot water, the nitrogen rapidly boils and chills the water vapor above it. This causes almost every evaporating water molecule to condense into tiny liquid droplets, producing a dense fog.

1. Heat water in a beaker until it is nearly boiling.
2. Place the beaker on a heat-safe surface in a well-ventilated area.
3. Using insulated gloves, carefully pour liquid nitrogen into the hot water.
4. Observe as the nitrogen boils violently and a thick, white fog rapidly forms above the beaker.
5. Point out that the fog is not actually nitrogen, but condensed water droplets created by cooling the escaping water vapor.

Liquid Nitrogen and boiling water = FOG! - MrGrodskiChemistry:

• Try using different temperatures of water (warm, hot, boiling) to compare the amount of fog produced.
• Use a strong flashlight or laser pointer to highlight the fog and make the droplets more visible.
• Place the beaker inside a large glass tank to contain the fog and create a dramatic rolling-cloud effect.

• Safety glasses required.
• Wear cryogenic gloves when handling liquid nitrogen.
• Use heat-resistant gloves if moving hot glassware.
• Perform in a well-ventilated area to prevent oxygen displacement.
• Use only borosilicate (Pyrex-type) glassware to reduce the risk of shattering.
• Stand back after pouring to avoid splashes of hot water or liquid nitrogen.

• Why does hot water produce more fog than warm water when liquid nitrogen is added?
• What exactly is the white cloud we see, and why isn’t it nitrogen gas?
• Why does cooling water vapor make it visible when it is normally invisible?
• How is this similar to the way clouds form in the atmosphere?
• Could this principle explain why you can sometimes “see your breath” on a cold day?