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 cannot be reversed by simple physical means. Examples include rusting and burning.

Front

What is an example of a physical change?

Back

Crumpled paper, pencil sharpening, and melting ice are examples of physical changes.

Front

What is an example of a chemical change?

Back

Baking cookies is an example of a chemical change because it involves a chemical reaction that produces new substances.

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What evidence indicates a chemical change has occurred?

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Evidence of a chemical change includes a change in color, the production of gas (bubbles), the formation of a precipitate (solid), and a change in temperature.

Front

What is rust?

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Rust is a chemical change that occurs when iron reacts with oxygen and moisture in the air, forming iron oxide.

Front

Is dissolving sugar in water a physical or chemical change?

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Dissolving sugar in water is a physical change because no new substance is formed and it can be reversed.

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What does it mean if a change is irreversible?

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An irreversible change is a change that cannot be undone or reversed, resulting in the formation of new substances.

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What is an example of evidence for a chemical change?

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A strong odor that wasn't present initially is evidence of a chemical change.

Front

What happens during a chemical reaction?

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During a chemical reaction, bonds between atoms are broken and new bonds are formed, resulting in the creation of new substances.