What type of change occurs when dry ice sublimes without melting?

When dry ice sublimes, it transitions directly from a solid state to a gaseous state without passing through a liquid phase. This process is an example of a physical change because it involves a change in the state of matter without altering the chemical composition of the substance. The molecular structure of carbon dioxide remains intact throughout the sublimation process.

In a physical change, the identity of the substance does not change, even though its form or state might. Since dry ice (solid carbon dioxide) simply changes into carbon dioxide gas without any chemical reaction taking place, this reinforces that sublimation is indeed a physical change.

In contrast, a chemical change involves a transformation that alters the chemical identity of a substance, resulting in new substances being formed. Sublimation does not meet this criterion, solidifying the classification as a physical change.