How do mixtures differ from pure substances? Give an example in which a pure substance, table salt, has different properties from a mixture that also contains table salt.
Pure substances have constant properties and constant composition, as they consist of particles of the same type.
For example, table salt is composed only of sodium chloride molecules.
The mixture has a variable composition – substances can be mixed in any way. Each substance in the mixture has its own properties. Therefore, the mixture consists of different types of particles.
For example, sea water is a solution of various salts, including sodium chloride, in water. Therefore, seawater contains not only water molecules, but also sodium chloride molecules (and molecules of other salts).
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