Chemical substance

A chemical substance is any material with a known chemical composition.^[1] For example, water has the same properties and the same ratio of hydrogen to oxygen whether it came from a river or was made in a laboratory. Typical chemical substances found in the home include water, salt and bleach. Generally, substances exist as a solid, a liquid, or a gas, and may change between these phases of matter when there are changes in temperature or pressure.

Water and steam are two different forms of the same chemical substance

Gallery

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  Gray silicon powder, an element. All the other ones are chemical compounds.
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  White sodium chloride
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  Pink hydrated (with water) manganese (II) chloride
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  Brown manganese (II) carbonate
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  Black copper (II) oxide
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  Red hydrated (with water) cobalt (II) chloride
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  Orange potassium dichromate
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  Yellow sodium chromate
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  Green hydrated (with water) copper (II) chloride
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  Blue hydrated (with water) copper(II) sulfate
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  Purple anhydrous (without water) chromium (III) chloride