What are physical and chemical changes?

Answer

Physical changes do not produce new substances, but chemical changes do produce new substances. A physical change is concerned with states of matter. Melting, vaporization, freezing, sublimation and condensation are physical changes. Melting an ice cube is a physical change because the substance remains as water. Most physical changes are reversible. Crushing a can, boiling water, breaking glass, chopping wood, mixing sand and water, and shredding paper are physical changes.

Chemical changes occur on the molecular level. The change produces a new substance. Chemical changes include combustion, synthesis, oxidation, neutralization and decomposition. For example, iron rusting is an instance of a chemical change. Food metabolism, burning wood, mixing and acid with a base, baking a cake and using a chemical battery are also examples of chemical changes.

A chemical change can be determined by evaluating if a reaction has occurred. A chemical reaction may have occurred if a change in light, heat, color, gas production, odor or sound is produced. If a precipitate develops, then a chemical change has occurred. An odor is a sign of a chemical change because it is evidence that decomposition is occurring. For example, a rotten egg produces an odor as it transforms into a new substance.

Q&A Related to "What are physical and chemical changes?"
A physical change is a change that happens to an object or substance through physical reactions. A chemical change is a change that happens to an object or substance through chemical
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a chemical change has properties like tarnishing,rusting , burning,and photosyntesis also there is always a reaction and something new and a phsical change has properties like odor,
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physical changes are anything that can be undone, eg crumpling paper chopping wood building with legos freezing water boiling water dissolving salt water chemical reactions can't
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they are both changes and both are matter.
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