Physical & 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 can be indicated by changes such as color change, gas production, or precipitate formation.

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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 temperature, production of gas, formation of a precipitate, and a change in color or odor.

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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 happens to the temperature during an exothermic reaction?

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In an exothermic reaction, the temperature of the surroundings increases because heat is released.

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What happens to the temperature during an endothermic reaction?

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In an endothermic reaction, the temperature of the surroundings decreases because heat is absorbed.

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What is rusting?

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Rusting is a chemical change that occurs when iron reacts with oxygen and moisture in the environment, forming iron oxide (rust).

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What is an example of a physical change?

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An example of a physical change is melting ice into water.

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What is an example of a chemical change?

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An example of a chemical change is baking a cake, where ingredients react to form a new substance.