Chemical and Physical Changes

Chemical Changes

• a chemical change produces a new substance 
• the change cannot be undone
• the old matter is no longer present
• the original matter cannot be recovered

Rust forming on a nail

Physical Changes

• a physical change does not produce a new substance
• changes in state or phase such as melting, freezing, condensation and sublimation are physical changes
• you can return the substance back into its original state and vice versa

Ice melting can be turned back to ice

How to tell the difference ?
A chemical change makes a substance that wasn't there before. There may be clues that a chemical reaction took place, such as light, heat, colour change, gas production, odor, or sound. The starting and ending materials of a physical change are the same, even though they may look different.


Janine R.