Physical and Chemical Changes

Front

What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting, freezing, and dissolving.

Front

What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. It involves a chemical reaction and changes the composition of the original substance. Examples include rusting, burning, and digestion.

Front

What are some indicators of a chemical change?

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Indicators of a chemical change include color change, temperature change, gas production (bubbles), formation of a precipitate, and change in odor.

Front

What are some indicators of a physical change?

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Indicators of a physical change include changes in state (solid, liquid, gas), shape, size, and texture without altering the substance's chemical identity.

Front

Is melting ice a physical or chemical change?

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Melting ice is a physical change because it changes from solid to liquid without changing its chemical composition (H2O).

Front

Is burning wood a physical or chemical change?

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Burning wood is a chemical change because it transforms the wood into ash, smoke, and gases, creating new substances.

Front

What happens to the molecules during a physical change?

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During a physical change, the arrangement of molecules may change, but the molecules themselves remain the same and retain their chemical properties.

Front

What happens to the molecules during a chemical change?

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During a chemical change, the bonds between molecules break and new bonds form, resulting in the creation of new substances with different properties.

Front

Can a physical change be reversed?

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Many physical changes can be reversed, such as freezing and melting, but some may not be easily reversible, like breaking a glass.

Front

Can a chemical change be reversed?

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Chemical changes are often not easily reversible. For example, burning paper cannot be reversed to get the original paper back.