A pure substance is one which is made up of a same type of molecule.And in real life we come across very few examples of pure substances.
A substance can be said to be pure if it has a homogeneous appearance and an uniform color throughout its matter.
These materials are very hard to find in regular life as most of them are mixed with some or other substances. But still some of them can be listed as pure substances like
- Rain water (or distilled water)
- Metals like iron, mercury, silver
- Organic compounds like naphthalene.
- Extracts like camphor
The tap water or river water looks homogeneous. But still their chemical composition could vary due to dissolved salts and other substances. But rain water is very pure till reaches the ground and gets mixed up. It has only molecules of water (H2O) making it a pure substance.
Graphite: This is another pure substance made of carbon. It is grey in color with homogeneous texture. Graphite has just carbon atoms and nothing else.
Metals like iron, silver, mercury are pure substances again.
They have same appearance and are made of individual metal atoms.
Diamond: The hardest substance diamond is also pure form of carbon.
Naphthalene: It is a white substance which we use to keep clothes free from insects and also remove odor in the toilets.
Naphthalene is a volatile solid substance. Due to this property, it is obtained as pure form.
Camphor: This also another volatile organic compound. And in most cases, this camphor is a pure substance without any ad mixtures.
Other substances which are in pure form are sugar, sodium hydrogen carbonate etc. Besides we can also obtain liquids like the ethanol, acetone and other in pure form as 100% concentration.
On the other hand most chemicals, medicines, packed material including table salt can be having mixture of other elements to a certain degree. Thus they cannot be called as pure substances.