Question

Complete the reaction:
$S{O}_3+H_{2}O\to$

Answer 1

Hint: A very common reaction which generally occurs in the atmosphere is when oxides of sulphur are present as pollutants, and it reacts with the moisture present in the environment. It is a hydrolysis reaction. The acid formed falls to the ground as the acid rain.

Complete answer:
Sulphur trioxide reacts with water to produce sulphuric acid. This type of reaction is called a hydrolysis reaction. In the hydrolysis reaction water is used to break down the bonds of a particular substance. Dissolving a salt of weak acid or weak base is an example of hydrolysis reaction. It may be endothermic or exothermic in nature here the reaction given to us is highly exothermic.
 Hydrolysis reactions are opposite dehydration reactions. Dehydration reaction involves the loss of water molecules. In hydrolysis reactions water molecules get attached to two parts of molecules. One part will get protons and the other will get hydroxide ions. The reaction of water with another chemical compound results in the formation of two or more products. Hydrolysis also helps in breaking down fats proteins and complex carbohydrates in food. The most common type of hydrolysis is salt hydrolysis. It refers to the reaction of salt with water where it involves the interaction between cations and anions of salt and water.
The reaction for hydrolysis of sulphur trioxide is given as:
$S{O}_3+H_{2}O\to H_{2}S{O}_4$
Here in the equation there are four oxygen atoms on the reactant side and also on the product side. Similarly both sulphur and hydrogen atoms are also balanced.
Hence the required balanced chemical equation is:
$S{O}_3+H_{2}O\to H_{2}S{O}_4$
This is the reaction used to produce sulphuric acid by burning sulphur into $S{O}_2$ and then converting into $S{O}_3$ , then reacting $S{O}_3$ with water.

Note:Sulphur trioxide is not directly dissolved in water because dissolution of sulphur trioxide is a highly vigorous reaction and produces a large amount of heat that it can’t be controlled.
There is a formation of moist tiny droplets which can corrode the tank pipes so sulphur trioxide is dissolved in concentrated sulphuric acid to produce oleum $H_2{S}_2{O}_7$ which can be diluted with required amount of water to yield sulphuric acid that is $$98$$ by mass.