What Is Dry Ice? How Solid CO₂ Turns Straight into Gas
From stage fog to frozen shipping
Dry ice has a surface temperature of -78.5°C. Compared to regular ice melting at 0°C, it's on a completely different level.
Sublimation
The phenomenon where a solid converts directly to gas without passing through liquid is called sublimation. That's why dry ice "shrinks without melting."
At 1 atmosphere of pressure, CO₂ cannot exist as a liquid. So when you place solid CO₂ (dry ice) at room temperature, it goes straight to gas. Water vapor in the surrounding air condenses on contact with this cold, creating white fog.
Dry Ice in Daily Life
Food delivery: Used for ice cream and frozen food shipping. Since it doesn't melt into water, packaging stays dry.
Stage effects: Fog effects in performance venues. Drop dry ice into warm water and it sublimes rapidly, producing dense fog.
Science experiments: Put dry ice in soapy water and you get giant bubbles inflated with CO₂. Kids love it.
Safety
Bare-hand contact causes frostbite. At -78.5°C, skin cells freeze almost instantly. Gloves are essential. Using large amounts in enclosed spaces also risks oxygen depletion as CO₂ concentration rises.
How It Works
CO₂ cannot exist as liquid at 1 atm → solid converts directly to gas (sublimation)
Water vapor around dry ice (-78.5°C) cools and condenses → white fog appears
Placing in warm water dramatically increases sublimation rate → dense fog effect