Physical Changes and Chemical Reactions

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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 process that involves the transformation of one or more substances into different substances with different properties. Evidence includes color change, gas production, and formation of a precipitate.

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What evidence indicates a chemical reaction has occurred?

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Evidence of a chemical reaction includes unexpected temperature changes, color changes, gas production, and the formation of a new substance.

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What happens during rusting?

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Rusting is a chemical change where iron reacts with oxygen and moisture in the environment to form iron oxide (rust), which is a new substance.

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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.

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What is the difference between a physical change and a chemical change?

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A physical change does not alter the chemical composition of a substance, while a chemical change results in the formation of new substances.

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What is an example of a physical change?

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Freezing water is an example of a physical change, as it changes from liquid to solid without changing its chemical structure.

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What is an example of a chemical change?

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Burning wood is an example of a chemical change, as it transforms the wood into ash, smoke, and gases.

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What does it mean if a gas is produced during a reaction?

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The production of gas during a reaction typically indicates that a chemical change has occurred.

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What is an endothermic reaction?

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An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a temperature decrease.