Physical and Chemical 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 the rearrangement of atoms. Examples include burning, rusting, and digestion.

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How can you identify a physical change?

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You can identify a physical change if the substance's appearance changes but its chemical identity remains the same. Common indicators include changes in state (solid, liquid, gas) or shape.

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How can you identify a chemical change?

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You can identify a chemical change if the substance undergoes a transformation that produces new substances. Indicators include color change, gas production, temperature change, or the formation of a precipitate.

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Is melting ice a physical or chemical change?

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

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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.

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What happens to the molecules during a physical change?

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During a physical change, the molecules may move closer together or further apart, but their chemical structure remains unchanged.

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What happens to the molecules during a chemical change?

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During a chemical change, the molecules rearrange to form new substances with different chemical properties.

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Is dissolving sugar in water a physical or chemical change?

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Dissolving sugar in water is a physical change because the sugar can be recovered by evaporating the water, and its chemical structure remains unchanged.

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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 forms iron oxide, a new substance, through a reaction with oxygen and moisture.