why sulphur trioxide is not directly added to water to form sulphuric acid during contact process?

Answer 1

The reaction would be:

SO3 (g) + H2O (l) → H2SO4 (l)

This reaction is highly exothermic. Enough heat is generated to vaporize the aqueous solution of Sulfuric acid that would be formed. In order to control this on an industrial scale, a great amount of energy would be need to remove this generated heat. This would be costly, driving up the final price of the H2SO4 produced.

In addition, the vaporized H2SO4 is very difficult to deal with. This is super acid rain and even if contained is highly corrosive.

By dissolving the Sulphur trioxide in Sulphuric acid, oleum is formed:

SO3 (g) + H2SO4 (l) → H2S2O7 (l)

This reaction does generate as much heat, an in a plant which is making H2SO4, the cost of the acid is negligible.

Answer 2

Contact Process Of Sulphuric Acid

Answer 3

If sulfur trioxid is dissolved in sulphuric acid it hereby forms "smoking sulphuric acid". This can be transported to the users, where the the normal low or high concentrated sulphuric acid is needed. They can add themselves as much or as little water as they need for their purposes. So on the way from production to the users no transport costs for water are to be paid for.

Answer 4

sulphur trioxide, SO3 is very unstable.
when SO3 is poured directly into water the reaction will be very
vigorous, a lot of heat will be given off.
results, a large cloud of sulphuric acid, H2SO4is produced which is corrosive and causes pollution in the air.

Answer 5

It forms a highly corrosive and toxic mist of sulphuric acid, which fills the factory!

Answer 6

the reaction is extreemly violent. sulphur trioxide can be added to water but only in very small quantities at a time, therefore it would be ineffcient industrially

Answer 7

I was wondering the same thing too today