Chemical and Physical Changes

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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 chemical composition of the substance. Examples include burning, rusting, and souring milk.

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Example of a physical change: melting ice.

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Melting ice is a physical change because the ice (solid water) changes to liquid water without changing its chemical structure.

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Example of a chemical change: baking a cake.

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Baking a cake is a chemical change because the ingredients undergo a chemical reaction to form a new substance (the cake) that has different properties.

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What happens during a physical change?

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During a physical change, the form or appearance of a substance changes, but its chemical identity remains the same.

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What happens during a chemical change?

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During a chemical change, the substances involved undergo a chemical reaction, resulting in the formation of new substances with different properties.

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Is freezing water a physical or chemical change?

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Freezing water is a physical change because it changes from liquid to solid without altering its chemical composition.

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Is rusting of iron a physical or chemical change?

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Rusting of iron is a chemical change because it involves a reaction with oxygen to form iron oxide, a new substance.

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What is an example of a reversible physical change?

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An example of a reversible physical change is melting ice, which can be frozen back into ice.

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What is an example of an irreversible chemical change?

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An example of an irreversible chemical change is burning wood, which cannot be turned back into wood after it has burned.