Oxygen & Sulphur

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Symbol : O,
Molecule formula — O2,
Atomic Number — 8,
Mass Number — 16
Element - P-block

Occurrence and Preparation of Oxygen Gas :
» Oxygen gas was firstly invented by a Sweden based scientist Scheele in 1772.
» It is a colourless, odourless gas, which is slightly heavier than atmospheric air.
» It reduces into a deep blue liquid on cooling, it doesn’t bum itself but favours the process of combustion.
» A mixture of helium and hydrogen gas is used in the artificial inhalation.

» There are three isotopes of oxygen — 8O16, 8O17, and 8O18


Symbol: S,
Atomic Number —16,
Mass Number — 32

Allotropes of Sulphur

1. Crystalline Allotropic Forms :
    (a) Rhombic or Octahedral or a-sulphur
    (b) Prismatic or Monoclinic or p-sulphur

2. Non-crystalline Allotropic Forms :
    (a) Plastic sulphur
    (b) White sulphur
    (c) Milky sulphur

Compounds of Sulphur

1. Sulphur Dioxide (SO2) :
During volcanic eruption, the main gas which releases is sulphur dioxide, and it is a colourless, suffocating, and a gas of bitter smell. This gas is also used as an antichlor. It exhibits the property of bleaching action, but it is temporary. The structure of SO2 is angular.

2. Sulphuric Acid (H2SO4) :
It is called chemical king of all the acids, and it is also known as oil of vitriol. On the industrial level, H2SO4 is manufactured by two processes-Contact process and Lead Chamber process.

3. Hydrogen Sulphide (H2S) :
During volcanic eruption, hydrogen sulphide gas is also released in small amount. This is basically a colourless gas, which is poisonous (toxic), and its smell is like rotten eggs.

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