H2SO4 is a strong dibasic acid, corresponding to the highest degree of sulfur oxidation (+6). Under normal conditions, the concentrated sulfuric acid - heavy, oily liquid is colorless and odorless. If the molar ratio of SO3:H2O <1, it is an aqueous solution of sulfuric acid if > 1 - a solution of SO3 in sulfuric acid (oleum).

H2SO4 is a strong dibasic acid, corresponding to the highest degree of sulfur oxidation (+6)

H2SO4 in concentrated form when heated is pretty strong oxidizing agent; oxidizes HI and HBr to partially free of halogens, carbon to CO2, sulfur - to SO2, oxidizes many metals (Cu, Hg, and others.). The concentrated sulfuric acid is reduced to SO2.

Concentrated H2SO4 absorbs water vapor, so it is used for the drying of gases, liquids and solids, for example, in a desiccator. However, concentrated H2SO4 is partially reduced with hydrogen, because of what can not be used for its drying. Splitting off water from organic compounds and leaving the carbon black, concentrated sulfuric acid, leads to charring the wood, sugar and other substances.

Diluted H2SO4 interacts with all metals in the electrochemical series stresses the left of hydrogen to its release. Sulfuric acid also reacts with basic oxides, and water to form a sulfate. Qualitative reaction to sulfuric acid and its soluble salts is their interaction with the soluble salts of barium, whereby a white precipitate of barium sulfate is insoluble in water and acids.

Consider an interesting question. Why after pumped concentrated H2SO4 or oleum steel tanks should be tightly closed immediately?

Once concentrated H2SO4 or oleum is pumped with steel railway tanks, they must be sealed immediately. If the tank hatch open, the remains of H2SO4 if oleum will eagerly absorb atmospheric moisture, and dilute acid will slowly corrode iron. Concentrated H2SO4 and oleum with iron in the cold do not respond as they passivate the surface.