Q:

What are physical and chemical changes?

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Quick 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.

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Full Answer

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.

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Related Questions

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    What does "chemical reaction" mean?

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    The term "chemical reaction" refers to any process that changes a set of chemical substances to another. That is, the substances that are put into a chemical reaction are different, on a molecular level, from those that result.

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    What are physical properties?

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    What are six indicators of a chemical change?

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    Harper College explains that forming a precipitate, color changes, gas formation and temperature change are signs of a chemical change. The University of California, Davis adds that the presence of odor also indicates a chemical change. There are only five indicators of a chemical change.

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    What is the main function of enzymes?

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