Physical and 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 changes in state (like melting or freezing), shape, or size.

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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 the breaking and forming of bonds between atoms, leading to a change in the chemical composition of the substance. Examples include rusting, combustion, and digestion.

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What are some indicators of a chemical change?

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Indicators of a chemical change include a change in color, the production of gas (bubbles), the formation of a precipitate, a change in temperature, and the emission of light.

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What are some examples of physical changes?

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Examples of physical changes include melting ice, boiling water, dissolving sugar in water, and breaking a glass.

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What are some examples of chemical changes?

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Examples of chemical changes include burning wood, baking a cake, rusting iron, and souring milk.

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How can you differentiate between physical and chemical changes?

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You can differentiate between physical and chemical changes by observing whether the substance's chemical composition changes. If it does, it's a chemical change; if it doesn't, it's a physical change.

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What happens to the molecules during a physical change?

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During a physical change, the arrangement of molecules may change, but the molecules themselves remain the same and retain their chemical properties.

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What happens to the molecules during a chemical change?

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During a chemical change, the bonds between atoms are broken and new bonds are formed, resulting in the creation of new substances with different chemical properties.

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Can physical changes be reversed?

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Many physical changes can be reversed, such as freezing and melting, but some may not be easily reversible, like breaking a glass.

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Can chemical changes be reversed?

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Chemical changes are often not easily reversible. For example, once wood is burned, it cannot be turned back into wood.