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Acids and Alkalis

Manufacture of Sulfuric Acid  -  The Contact Process.

Sulfur trioxide will dissolve in water to make sulfuric acid.

sulfur trioxide  +   water   arrow      sulfuric acid
SO3(g)       +          H2O(l)     arrow     H2SO4(aq)

The reaction is highly exothermic and produces an acid mist
which is difficult to condense.

In practice it is easier to dissolve sulfur trioxide
in concentrated (98%) sulfuric acid to form oleum.

sulfur trioxide  +   sulfuric acid   arrow      oleum
SO3(g)           +            H2SO4(aq)        arrow     H2S2O7(l)

Oleum is sometimes called fuming sulfuric acid.
Water
is then carefully added to oleum
to remake concentrated (98%) sulfuric acid.

oleum     +      water      arrow   sulfuric acid
H2S2O7(l)     +     H2O(l)     arrow        2H2SO4(aq)

Sulfuric acid has many uses in industry.

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