Reversible Changes
Elementary School
Definition
Physical changes that can be undone to return a material to its original state, such as melting ice back from water or dissolving and then evaporating salt. They contrast with chemical changes, which usually cannot be reversed.
Worked examples
Ice melting to water, then freezing back to ice
The water molecules rearrange but stay H₂O — no new substance forms, so the change reverses easily.
Salt dissolved in water, then water evaporated to recover solid salt
Dissolving is reversible because the salt crystals can reform when the water leaves.
Common mistakes
- Burning wood is reversible because you can collect the ashes → Burning wood is a chemical change and cannot be reversed Ashes and gases are new substances; you cannot turn them back into wood.
- All physical changes are reversible → Some physical changes are hard to reverse (e.g., mixing sand and salt) Reversibility means easily undone; separating a mixture can be difficult even if no chemical change occurred.
- Cooking an egg is reversible because it's just heating → Cooking an egg is a chemical change and irreversible Heat causes proteins to permanently change structure; the egg cannot return to its raw state.
Where you'll use it next
You'll apply reversible changes when studying phase changes, solutions, mixtures, and separation techniques in chemistry, and later distinguish them from irreversible chemical reactions.
See also
Physical ChangesStates of MatterChemical reactionSeparation MethodsMaterial PropertiesTypes of Changes
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026