Physical and Chemical Changes Review

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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 occurs when a substance transforms into a different substance with different properties. This often involves a chemical reaction, such as rusting or burning.

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What happens to molecules during boiling?

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During boiling, heat is added to the liquid, causing the molecules to move faster and eventually change into gas, forming bubbles.

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What happens to molecules during freezing?

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During freezing, heat is removed from the liquid, causing the molecules to slow down and arrange themselves into a solid structure.

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What is condensation?

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Condensation is the process where gas turns into liquid when it cools down, often seen as water droplets on a cold surface.

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What is evaporation?

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Evaporation is the process where liquid turns into gas at temperatures below its boiling point, often occurring at the surface of the liquid.

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What is the difference between melting and freezing?

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Melting is the process of a solid turning into a liquid when heat is added, while freezing is the process of a liquid turning into a solid when heat is removed.

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What is an example of a physical change?

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An example of a physical change is ice melting 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 iron rusting when it reacts with oxygen.

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What is the role of heat in changes of state?

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Heat plays a crucial role in changes of state; it can be added to cause melting or boiling, or removed to cause freezing or condensation.