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Give the principle of contact process for the manufacture of sulphuric acid. 3 Give an equation to show oxidising property of sulphuric acid.

Give the principle of contact process for the manufacture of sulphuric acid. 3
Give an equation to show oxidising property of sulphuric acid.

Grade:9

1 Answers

Sunil Kumar FP
askIITians Faculty 183 Points
9 years ago
The Contact Process:

makes sulphur dioxide;

convers the sulphur dioxide into sulphur trioxide (the reversible reaction at the heart of the process);

converts the sulphur trioxide into concentrated sulphuric acid.


Making the sulphur dioxide

This can either be made by burning sulphur in an excess of air:
S +O2----SO2
. . . or by heating sulphide ores like pyrite in an excess of air:
4FeS2 +11O2------2Fe2O3 +8SO2

In either case, an excess of air is used so that the sulphur dioxide produced is already mixed with oxygen for the next stage.

Converting the sulphur dioxide into sulphur trioxide
2SO2 +O2 ----2SO3
This is a reversible reaction, and the formation of the sulphur trioxide is exothermic.

.

Converting the sulphur trioxide into sulphuric acid

This can't be done by simply adding water to the sulphur trioxide - the reaction is so uncontrollable that it creates a fog of sulphuric acid. Instead, the sulphur trioxide is first dissolved in concentrated sulphuric acid:
H2SO4 +SO3----H2S2O7
The product is known asfuming sulphuric acidoroleum.

This can then be reacted safely with water to produce concentrated sulphuric acid - twice as much as you originally used to make the fuming sulphuric acid.
H2S2O7 +SO3----2H2SO4

oxidising property of sulphuric acid.
H2SO4 +2H+ +2e- -----SO2 +2H2O

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