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

Front

What happens to the molecules during a physical change?

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During a physical change, the molecules of a substance may change their arrangement or state (solid, liquid, gas) but their chemical structure remains the same.

Front

What happens to the molecules during a chemical change?

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During a chemical change, the molecules of a substance undergo a chemical reaction, resulting in the formation of new substances with different properties.

Front

Is melting a chocolate bar a physical or chemical change?

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Melting a chocolate bar is a physical change because it changes the state of the chocolate from solid to liquid without altering its chemical composition.

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Is digesting food a physical or chemical change?

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Digesting food is a chemical change because it involves breaking down food into new substances that the body can use.

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What is an example of a physical change?

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An example of a physical change is dissolving sugar in water, where the sugar retains its chemical identity.

Front

What is an example of a chemical change?

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An example of a chemical change is lighting a match, which produces new substances such as ash and gases.

Front

What is the significance of observing color change in a reaction?

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A color change often indicates a chemical change has occurred, suggesting that new substances with different properties have formed.

Front

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

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A physical change alters the form or appearance of a substance without changing its chemical composition, while a chemical change results in the formation of new substances.