EVERYDAY SCIENCE

Detailed explanation-1: -Dry Ice is the common name for solid carbon dioxide (CO2 ). It gets this name because it does not melt into a liquid when heated; instead, it changes directly into a gas. (This process is known as sublimation).

Detailed explanation-2: -Emphasize that these are physical changes. The bubbles are produced from the sublimation of solid carbon dioxide to carbon dioxide gas because the water raises the temperature of solid carbon dioxide above its sublimation temperature.

Detailed explanation-3: -This must be a chemical change, because a new substance-“fog”-forms.” Actually, dry ice undergoes a physical change when it sublimates from the solid to the gaseous state without first melting into a liquid. The same carbon dioxide is still present, it just undergoes a phase change to become a colorless gas.

Detailed explanation-4: -Sublimation is a physical change. When a substance sublimes, it changes from a solid to a gas without going through the liquid phase. This does not result in a chemical change, though. An example of a common substance that goes through sublimation is dry ice.