During a chemical change, the following characteristics occur that do not happen during a physical change:
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Change in Chemical Composition: A chemical change results in the formation of one or more new substances with different chemical properties, whereas a physical change does not alter the composition of the substances involved (e.g., ice melting into water).
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Bond Breaking and Formation: In a chemical change, bonds between atoms are broken and new bonds are formed, leading to a rearrangement of atoms. This is not the case in a physical change, where the chemical structure remains the same.
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Energy Changes: Chemical changes often involve energy changes in the form of heat, light, or sound. For example, combustion releases energy, while photosynthesis absorbs energy. Physical changes can also involve energy changes, but they do not typically involve new substances being formed.
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Involvement of Reactants and Products: A chemical change involves reactants that transform into products, while physical changes do not create or destroy substances.
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Irreversibility: Many chemical changes are not easily reversible (e.g., burning wood into ash), whereas physical changes are usually reversible (e.g., freezing and melting water).
If you have specific examples to consider, please share them, and I can help pinpoint which align with chemical versus physical changes.