Contact Process - Part 1
Introduction
Contact process is an industrial method involving reversible reactions for manufacturing Sulphuric acid. It comprises 3 primary steps.
Step 1
Sulphur is combusted with oxygen to form sulphur dioxide. It's equation is :
S8 + 8O2 = 8SO2
The raw material needed for the contact process are sulphur, air, and water. Sulphur can be mined in various parts of the world, but large quantities are obtained from removing the impurities from fossil fuels (the process is known as desulphurisation)
The sulphur dioxide required for the generation of sulphuric acid is obtained industrially by burning sulphur ores such as zinc blende (ZnS).
2ZnS (s) + 3O2 (g) = 2ZNO (s) + 2SO2
Metal sulphide + oxygen = metal oxide + sulphur dioxide
Sulphur along, with the elements in Group 16, is known as calcogens, elements that forms ores.
Calcogens
The calcogens are the elements in Group 16 of the periodic table, which includes :- Oxygen, Sulphur, Selenium, Tellerium, and Polonium.
The word calcogens literally means "ore formers" (from Greek calcos = ore, -gen = formers). They are not the only non-metals that forms ores, but they are the most common non-metals found in ores.
They form compounds known called calcogenides.
Calcogens forms ores because they easily combine metals to form stable, insoluble compounds. how? It is due to
- high electronegativity
- moderate reactivity
- low solubility
They are not soluble since they are non-polar compounds. They form ionic compounds, but they are not polar compounds. why not? Their arrangements make them have no extra charge.