Answer
Solid carbon dioxide sublimes directly to the gas phase when heated, which is why solid $CO_{2}$ is called “dry ice.”
Work Step by Step
$CO_{2}$ has a triple point at $-56^{\circ}C$ and 5.1 atm. At atmospheric pressure, therefore, the liquid phase of $CO_{2}$ does not exist. Solid carbon dioxide sublimes directly to the gas phase when heated, which is why solid $CO_{2}$ is called “dry ice.”
