Acids and Alkalis

Manufacture of Sulfuric Acid  -  The Contact Process.

How is Sulfur trioxide made into Sulfuric Acid?

Sulfur trioxide will dissolve in water to make sulfuric acid.

This is the balanced chemical equation for the reaction of
sulfur trioxide with water.

sulfur trioxide     +      water           sulfuric acid
       SO_3(g)         +      H₂O_(l)             H₂SO_4(aq)

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

In industry it is easier to dissolve sulfur trioxide
in concentrated (98%) sulfuric acid to form oleum
(oleum is sometimes called fuming sulfuric acid).

This is the balanced chemical equation for the reaction of
sulfur trioxide with sulfuric acid.

sulfur trioxide     +      sulfuric acid                oleum
       SO_3(g)            +          H₂SO_4(aq)             H₂S₂O_7(l)

Water is carefully added to oleum to remake concentrated (98%) sulfuric acid.

This is the balanced chemical equation for the reaction of
oleum with water.

oleum      +       water          sulfuric acid
H₂S₂O_7(l)    +      H₂O_(l)             2H₂SO_4(aq)

gcsescience.com     Contents      The Periodic Table     Index      Quizzes     gcsescience.com