Dry ice is solid carbon dioxide; it is called “dry” because it goes directly from a solid to a gas without becoming a liquid under ordinary conditions. Draw a picture that shows what the carbon dioxide molecules might look like as a solid and as a gas.

Strategy To answer conceptual questions such as this, we must depict the differences between the two phases. Our drawing can be schematic, but it must imply the differences clearly. In this case, we know that a solid will have closely packed molecules, whereas a gas will exhibit significant space between particles.