Liquid Nitrogen vs Boiling Water

What happens when liquid nitrogen (boiling point: –196 °C) is poured into recently boiled water? In this striking chemistry demonstration, you'll witness a dramatic plume of white "smoke", accompanied by a series of sharp cracking and popping sounds. But what exactly is going on?

This reaction is an excellent example of a physical process driven by extreme temperature differences:

🔥 The hot water rapidly transfers energy to the nitrogen, causing it to boil violently and expand nearly 700 times in volume as it becomes nitrogen gas.

🌫️ The resulting cloud is not actually smoke—it's a fog of tiny water droplets. As the nitrogen evaporates, it rapidly cools the surrounding water vapour, causing it to condense into a visible mist, just like how you see your breath on a cold day or dry ice fog at ground level.

🔊 The initial cracking or popping noise comes from the violent boiling and rapid localised freezing as the cryogenic nitrogen makes contact with the hot water surface. Micro-explosions of steam and gas bubbles form instantly and burst due to the rapid energy exchange, giving the effect of audible snaps or bangs.