Why is solid carbon dioxide called dry ice?
Solid carbon dioxide is known as dry ice. Because it looks like ice and because when it “melts” (it actually sublimes) it goes from solid straight to gas, no liquid, hence dry ice.
It is called dry ice because the solid turns to gas when heated, without turning into a liquid first. However, if we apply pressure and heat, we can turn it into a liquid, and sure, we can swim in it. We know this because of something called the phase diagram of carbon dioxide (the "stuff" of dry ice).
More clearly
Dry ice is basically solidified carbon dioxide and is called so because the gas on solidifying gives an appearance similar to that of ice. Unlike ordinary ice, it does not melt into a liquid but changes directly into CO2gas, a phenomenon known as sublimation. It changes into a gaseous state at and above -78.5 degrees Celsius. As this temperature is much lower than water, it is much colder than water ice. Its density varies from1.2 - 1.6 g / cm3. It is therefore denser than water. It is mainly used as a cooling agent because it has a temperature lower than that of water ice. It is used for preserving frozen foods, ice cream, etc