Physical and Chemical Changes: What's the Difference?

Physical Changes

Physical changes are changes that do not involve a change in the chemical makeup of a substance. These changes are usually reversible, meaning the substance can be returned to its original state. For example, when water freezes and becomes ice, it is still H2O, just in a different state of matter. Other examples of physical changes include melting, boiling, tearing, and crushing.

Chemical Changes

Chemical changes, on the other hand, result in the formation of new substances with different chemical compositions. These changes are usually irreversible. An example of a chemical change is when iron rusts. The iron combines with oxygen in the air to form iron oxide, which is a completely different substance. Other examples of chemical changes include burning, cooking, and digesting food.

Key Differences

One key difference between physical and chemical changes is the reversibility of the change. Physical changes are usually reversible, while chemical changes are usually irreversible. Another key difference is the formation of new substances with different chemical compositions in chemical changes, compared to no new substances being formed in physical changes.