Glossary
physical change
A physical change alters a substance's size, shape or state — melting, freezing, dissolving, tearing — without making a new substance. The material is the same before and after.
A physical change alters the form of a substance but not its identity. Ice, water and steam are the same substance in three states; a torn sheet of paper is still paper; salt stirred into water is still salt, and evaporating the water leaves it behind. Because no new substance appears, most physical changes are easy to reverse — melt and freeze, dissolve and evaporate.
Changes of state are the ones you will see most, and each has a name worth holding: melting is solid to liquid, freezing is liquid to solid, evaporation and boiling are liquid to gas, condensation is gas to liquid, and sublimation is solid straight to gas, as dry ice does. Cutting, grinding, bending, stretching and dissolving are the ordinary mechanical kinds.
The line between this and a chemical change is the whole question. A chemical change builds a new substance — rust, ash, the gas from a reaction — and is hard to reverse, while a physical change only rearranges the same material. A quick check is to ask whether a simple physical step would get the original back; if it would, the change was physical.
Taught in
Related terms
- chemical change — A chemical change makes a new substance — rusting, burning, cooking and reactions with an acid. The evidence is a change that is hard to reverse: a new color, a gas, a solid or heat.
- states of matter — The states of matter are solid, liquid and gas: a solid holds its own shape and volume, a liquid holds its volume but takes the shape of its container, and a gas holds neither.
Source: Official ASVAB — subtest descriptions (what each subtest asks) and the CAT-ASVAB scored-question counts (accessed 2026-09)