A pure substance is one that is made up of the same type of molecule. And in real life, we come across very few examples of pure substances.
A substance can be said to be of pure form if it has a homogeneous appearance and a 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
- Rainwater (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 rainwater is very pure till it 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 a homogeneous texture. Graphite has just carbon atoms and nothing else.
Metals like iron, silver, mercury are pure substances again.
They have the same appearance and are made of individual metal atoms.
Diamond: The hardest substance diamond is also a pure form of carbon.
Naphthalene: It is a white substance that we use to keep clothes free from insects and remove odor in the toilets.
Naphthalene is a volatile solid substance. Due to this property, it is obtained as a pure form.
Camphor: This also another volatile organic compound. And in most cases, this camphor is a pure substance without any admixtures.
Other substances that are in pure form are sugar, sodium hydrogen carbonate, etc. Besides, we can also obtain liquids like ethanol, acetone, and others in pure form at 100% concentration.
On the other hand, most chemicals, medicines, packed material, including table salt, can be having a mixture of other elements to a certain degree. Thus they cannot be called pure substances.