Question

Compare the type of change that occurs when an iron bar rusts and when a substance freezes. Use complete sentences to justify the type of change that occurs.

Answer 1

When a substance freezes, it’s molecules lose energy, but the identity of the substance is the same. (Ex: when water freezes, it’s still H2O, just in solid form) Therefore, this is a physical change.

When an iron bar rusts, a new compound is formed (iron oxide), so this is a chemical change.