Physical and Chemical Changes

Front

What is a physical change?

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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.

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What is a chemical change?

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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 substance. Examples include burning, rusting, and cooking.

Front

What is an example of a physical change?

Back

Cutting a piece of paper is an example of a physical change because it does not change the chemical composition of the paper.

Front

What is an example of a chemical change?

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Burning a piece of paper is an example of a chemical change because it transforms the paper into ash and smoke, creating new substances.

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What evidence indicates a chemical change has occurred?

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Evidence of a chemical change includes gas production, color change, temperature change, and the formation of a precipitate.

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What is a precipitate?

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A precipitate is a solid that forms and settles out of a liquid mixture during a chemical reaction.

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What happens to the properties of a substance during a physical change?

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The properties of a substance may change in appearance or state, but its chemical identity remains the same.

Front

What happens to the properties of a substance during a chemical change?

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The properties of a substance change completely, resulting in the formation of new substances with different chemical identities.

Front

Is sour milk a physical or chemical change?

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Sour milk is an example of a chemical change because it involves the fermentation process that alters the chemical composition of the milk.

Front

What is an example of a process that involves both physical and chemical changes?

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Chopping wood (physical change) followed by burning it (chemical change) is an example of a process that involves both types of changes.