Oxygen was first discovered by Swedish pharmacist Carl Wilhelm Scheele.In 1772 AD who obtained it by heating potassium nitrate, mercuric oxide, and many other substances. Oxygen gas is the necessary gas fro alive to animals and plants. It makes over 20% of the death atmosphere. It is an eighth element and chalcogen group of the periodic table. so its atomic number is 8, and the symbol of oxygen is "O". The molecular formula of oxygen is O2. The element and its compounds make up 49.2% by mass of the Earth’s crust, and about two-thirds of the human body. In the laboratory, it can be prepared by the electrolysis of water or by adding manganese(IV) oxide catalyst to aqueous hydrogen peroxide. It is a Nonmetallic chemical element. It is a colourless, odourless, and tasteless diatomic gas. Oxygen is the most important compound in water. Oxygen is commonly used to produced the steel, plastics, welding, cutting of steels, and oxygen therapy, rocket propellant. and life support systems in aircraft, submarines, spaceflight and diving.
Chemical properties of oxygen gas
| Gas | Oxygen |
| Melting point | −218.8°C (−425.84°F) |
| Boiling point | −183.0 °C (−297.4 °F) |
| Density | 1.429 g/L |
| when liquid | 1.141 g/cm3 |
| Isotopes | 4 |
| Ionic radius | 0.14 nm (-2) |
| Heat of vaporization | (O2) 6.82 kJ/mol |
| Molar heat capacity | (O2) 29.378 J/(mol·K) |
| Heat of fusion | (O2) 0.444 kJ/mol |
Physical properties of oxygen gas
- Oxygen is cloudless, odourless, tasteless diatomic gas.
- Oxygen is slightly heavier than air.
- Oxygen gas is slightly soluble in water.
- Oxygen gas is a poor conductor of heat and electricity.
- oxygen gas is neutral. so, it does not show any effects on litmus.
