As most people know… when added to hot water, dry ice creates fog. But why does this happen? Let’s take a look.
Dry ice is nothing but raw carbon dioxide (CO2). Dry ice needs to be at least -109.3 °F. Because dry ice is nothing but CO2, as its temperature rises and it “melts”, it turns directly in to the CO2 gas form. Dry ice bypasses the liquid stage. This process is called sublimation. When this happens in water, it creates tiny CO2 bubbles. These CO2 bubbles are very cold (this plays an important part). As these CO2 bubbles make their way to the top of the water and mix with the air, something fun happens. The cold CO2 bubbles, made from the dry ice, cause a sudden drop in temperature. This drop in temperature causes tiny droplets of water to in the surrounding air to form a visible fog.
Because the fog created is a mixture of water, air, and CO2, the gas is heavier then the air we breathe. This causes the fog to drop low to the ground. This fog stays around for a little bit until it warms up enough.