PURE SUBSTANCES

In everyday life, a pure substance can mean a substance that has had NOTHING ADDED to it, so it is UNADULTERATED and in its natural state, e.g. pure milk.

In Chemistry, a pure substance is a single element or compound, NOT mixed with any other substance.

You can tell whether a substance is pure or not by checking its MELTING or BOILING POINT.

Pure substances will always have a specific melting or boiling point, so if a substance deviates from the known boiling points, there are IMPURITIES present.

For example, SAMPLE 2 would be the PUREST out of the 4 samples, as it has the closest boiling point to PURE water.