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Chemical Properties of H2SO4

Reaction with water:

The hydration reaction of sulfuric acid is highly exothermic(chemical reaction that releases energy in the form of heat). One should always add the acid to the water rather than the water to the acid. Because the reaction is in an equilibrium that favors the rapid protonation of water, addition of acid to the water ensures that the acid is the limiting reagent. This reaction is best thought of as the formation of hydronium ions:

H2SO4 + H2O ? H3O+ + HSO4?

HSO4? + H2O ? H3O+ + SO42?

Because the hydration of sulfuric acid is thermodynamically (energy conversion involving heat and other forms of energy) favorable, sulfuric acid is an excellent dehydrating agent, and is used to prepare many dried fruits. The affinity of sulfuric acid for water is sufficiently strong that it will remove hydrogen and oxygen atoms from other compounds; for example, mixing starch (C6H12O6)n and concentrated sulfuric acid will give elemental carbon and water which is absorbed by the sulfuric acid (which becomes slightly diluted):

(C6H12O6)n ? 6n C + 6n H2O

The effect of this can be seen when concentrated sulfuric acid is spilled on paper; the cellulose reacts to give a burnt appearance, the carbon appears much as soot would in a fire. A more dramatic reaction occurs when sulfuric acid is added to a tablespoon of white sugar in a beaker; a rigid column of black, porous carbon will quickly emerge. The carbon will smell strongly of caramel due to the heat generated. Although less dramatic, the action of the acid on cotton, even in diluted form, will destroy the fabric.

As an acid, sulfuric acid reacts with most bases to give the corresponding sulfate. For example, the blue copper salt copper(II) sulfate, commonly used for electroplating and as a fungicide, is prepared by the reaction of copper(II) oxide with sulfuric acid:

CuO (s) + H2SO4 (aq) ? CuSO4 (aq) + H2O (l)

Concentrated sulfuric acid reacts with sodium chloride, and gives hydrogen chloride gas and sodium bisulfate:

NaCl + H2SO4 ? NaHSO4 + HCl

Manufactoring H2SO4

Most of the sulfuric acid manufactured is produced using the Contact Process.

Combustion Chamber

(combustion of sulfur) > Converter

(conversion of sulfur dioxide) > Absorption Tower

(sulfur trioxide absorbed