Explain the Contact process of manufacture of sulphuric acid.

Asked by haritsourabhharit | 15th Oct, 2010, 12:53: PM

Expert Answer:

Dear Student
Most of the sulfuric acid manufactured is produced using the Contact Process.
1.  Solid sulfur, S(s), is burned in air to form sulfur dioxide gas, SO2  
                                    S(s) + O2(g) -----> SO2(g)  
2.   The gases are mixed with more air then cleaned by electrostatic precipitation to remove any particulate matter  
 3.  The mixture of sulfur dioxide and air is heated to 450oC and subjected to a pressure of 101.3 - 202.6 kPa (1 -2 atmospheres) in the presence of a vanadium catalyst (V2O5) to produce sulfur trioxide, SO3(g), with a yield of 98%. 
                       2SO2(g) + O2(g) -----> 2SO3(g)
 Any unreacted gases from the above reaction are recylced back into the above reaction

4.   Sulfur trioxide, SO3(g) is dissolved in 98% (18M) sulfuric acid, H2SO4, to produce disulfuric acid or pyrosulfuric acid, also known as fuming sulfuric acid or oleum, H2S2O7.

                                SO3(g) + H2SO4 ------> H2S2O7
This is done because when water is added directly to sulfur trioxide to produce sulfuric acid
                                   SO3(g) + H2O(l) -----> H2SO4(l)

the reaction is slow and tends to form a mist in which the particles refuse to coalesce.

 5.  Water is added to the disulfuric acid, H2S2O7, to produce sulfuric acid, H2SO4
                            H2S2O7(l) + H2O(l) -----> 2H2SO4(l)
We hope that clarifies your query.
With Best Regards,

Answered by  | 15th Oct, 2010, 04:09: PM

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