A pure' material is one where there is only one substance in it (an element or compound). Steel is not a pure substance as it is made up of several other elements. Iron being among them.

Test for purity[edit | edit source]

A liquid will boil sharply at a constant temperature (e.g. water would boil at 100C). This is called the boiling point. An impure liquid will boil at a higher temperature if a solid impurity is dissolved in it. If it contains a liquid impurity with a lower boiling point, it will boil for a greater range of temperature. If a solid is pure, it melts sharply at its melting point. An impure solid will melt below this point.

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