CoachA pure substance is made of one single chemical species and nothing else: distilled water, a crystal of sugar, a gold ring of pure gold.
Examples
Example 8.11 (Four waters)
- Distilled water, made in a laboratory, is very nearly a pure substance: water and nothing else.
- Tap water is a homogeneous mixture: water with small amounts of dissolved substances (a drop dried on a dark plate leaves a white ring).
- Mineral water is a homogeneous mixture whose label gives the dissolved substances, in milligrams per litre.
- Sea water is a homogeneous mixture holding about of salts in each kilogram.