Chemical and Physical Changes

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What is a chemical change?

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A process where substances combine or break apart to form new substances, often accompanied by energy changes.

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What is a physical change?

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A change that affects one or more physical properties of a substance without altering its chemical composition.

Front

Example of a chemical change: A candle burning. What happens?

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The wax (a hydrocarbon) reacts with oxygen to produce carbon dioxide, water, and heat.

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Example of a chemical change: Iron turning into rust. What is the process called?

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Oxidation, where iron reacts with oxygen and moisture to form iron oxide (rust).

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Example of a chemical change: Acid cooking a raw egg. What occurs?

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The proteins in the egg undergo a chemical reaction, changing their structure and properties.

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Example of a physical change: Changing the shape of Play-Doh. What is the key characteristic?

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The material remains the same (Play-Doh), only its shape is altered.

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Example of a physical change: Smashing a bug. What happens?

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The bug's physical form is altered, but its chemical composition remains unchanged.

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What are indicators of a chemical change?

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Color change, temperature change, gas production, formation of a precipitate, or light emission.

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What are indicators of a physical change?

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Change in shape, size, state of matter (solid, liquid, gas) without altering the substance's chemical identity.

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Is melting ice a chemical or physical change?

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Physical change, as the ice (solid water) changes to liquid water without changing its chemical structure.