Changes and ECM

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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) and changes in 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 a chemical reaction and the rearrangement of atoms. Examples include rusting of iron and burning of wood.

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What is a homogeneous mixture?

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A homogeneous mixture is a mixture that has a uniform composition throughout. The individual components are not distinguishable. Examples include saltwater and air.

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What is a heterogeneous mixture?

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A heterogeneous mixture is a mixture in which the components are not uniformly distributed and can be easily distinguished. Examples include salad and sand mixed with iron filings.

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What is a pure substance?

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A pure substance is a material that has a constant composition and consistent properties throughout. It can be an element (like oxygen) or a compound (like water).

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What is an element?

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An element is a pure substance that cannot be broken down into simpler substances by chemical means. Each element is made up of atoms of the same type.

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What is a compound?

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A compound is a pure substance formed when two or more elements are chemically bonded together. Compounds have properties that are different from the individual elements that make them up.

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What is the law of conservation of mass?

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The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of the reactants equals the total mass of the products.

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What is a chemical reaction?

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A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. It involves breaking and forming bonds between atoms.

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What are reactants?

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Reactants are the starting substances in a chemical reaction that undergo change to form products.