Pure Substances and Mixtures

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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. Examples include elements and compounds.

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What is a mixture?

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A mixture is a combination of two or more substances where each substance retains its own properties. Mixtures can be homogeneous or heterogeneous.

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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. Examples include oxygen (O) and gold (Au).

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What is a compound?

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A compound is a pure substance formed when two or more elements chemically combine in fixed proportions. An example is carbon dioxide (CO2).

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What is a solution?

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A solution is a homogeneous mixture where one substance (the solute) is dissolved in another (the solvent), such as saltwater.

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What is the difference between a homogeneous mixture and a heterogeneous mixture?

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A homogeneous mixture has a uniform composition throughout (e.g., air), while a heterogeneous mixture has visibly different substances or phases (e.g., salad).

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What is an example of a pure substance?

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Examples of pure substances include distilled water, pure gold, and table sugar.

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What is the term for a mixture that has a uniform composition?

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The term is 'homogeneous mixture'.

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What is the term for a mixture that does not have a uniform composition?

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The term is 'heterogeneous mixture'.

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Which of the following is NOT a mixture: milk, lemonade, vegetable salad, or carbon?

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Carbon is NOT a mixture; it is an element.