Physical and Chemical Changes; Law of Conservation of Mass

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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.

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What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. Examples include rusting of iron, burning wood, and baking a cake.

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What is the Law of Conservation of Mass?

Back

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.

Front

What is an example of a physical change?

Back

Melting ice into water is an example of a physical change.

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What is an example of a chemical change?

Back

Iron rusting is an example of a chemical change.

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What is a chemical property?

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A chemical property is a characteristic of a substance that can only be observed during a chemical reaction, such as reactivity with air.

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What happens to mass during a chemical reaction?

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The total mass remains the same; however, if gases are released, the mass of the products may appear less than the reactants.

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Why is boiling water a physical change?

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Boiling water is a physical change because it remains water (H2O) and no new substance is formed.

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What is reactivity?

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Reactivity is a chemical property that describes how readily a substance combines chemically with other substances.

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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.