Review Physical and CHemical Properties and Changes

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What is reactivity?

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Reactivity is the ability of a substance to undergo a chemical reaction with another substance. For example, fluorine gas is highly reactive and can ignite materials spontaneously.

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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. For example, boiling water changes from liquid to gas but remains H2O.

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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. For example, iron rusting is a chemical change where iron reacts with oxygen to form iron oxide.

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What happens during boiling?

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During boiling, a liquid turns into vapor as it is heated. This is a physical change because the chemical structure of the substance remains the same.

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What is combustibility?

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Combustibility is the ability of a substance to catch fire and burn in the presence of oxygen. For example, wood is combustible.

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What is viscosity?

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Viscosity is a measure of a fluid's resistance to flow. For example, honey has a higher viscosity than water.

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What is the difference between physical and chemical properties?

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Physical properties can be observed without changing the substance's chemical identity (e.g., color, boiling point), while chemical properties can only be observed during a chemical reaction (e.g., reactivity with acid).

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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. The substance remains H2O, but its state changes from solid to liquid.

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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. The ingredients undergo a chemical reaction to form a new product.

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What is the significance of observing changes in matter?

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Observing changes in matter helps us understand whether a physical or chemical change has occurred, which is crucial in chemistry.