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Chemical & Physical Changes

Understanding Changes in Matter

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Fire indicates a chemical change.

Fire indicates a chemical change.

Christine, www.morguefile.com

Chemical and physical changes are related to chemical and physical properties.

Chemical Changes

Chemical changes take place on the molecular level. A chemical change produces a new substance. Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan, and mixing hydrochloric acid and sodium hydroxide to make salt and water.

Physical Changes

Physical changes are concerned with energy and states of matter. A physical change does not produce a new substance. Changes in state or phase (melting, freezing, vaporization, condensation, sublimation) are physical changes. Examples of physical changes include crushing a can, melting an ice cube, and breaking a bottle.

How to Tell Chemical & Physical Changes Apart

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, color change, gas production, odor, or sound. The starting and ending materials of a physical change are the same, even though they may look different.

More Examples of Chemical and Physical Changes
Physical and Chemical Changes Quiz
List of 10 Physical Changes
List of 10 Chemical Changes

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