H2SO4 is a covalent molecule with sulphur in a +6 oxidation state. The two oxygen atoms are linked to sulphur by double bonds while the other two oxygen atoms.
Are linked by single covalent bonds. Thus it has tetrahedral structure. Infact, sulphuric acid has an associated structure due to the presence of hydrogen bonds. As a result, it is a dense and viscous liquid and has a high boiling point of 590 K
Structure of H2SO4 H-bonding in conc. H2SO4
(i) H2SO4 is a strong dibasic acid. It neutralizes alkalies, liberates CO2 from carbonates and bicarbonates.
(ii) It reacts with more electropositive (than hydrogen) metals to evolve H2 and produces SO2 on heating with less electropositive metals hydrogen eg.,
H2SO4 + 2KOH —> K2SO4 + 2H2O;
Cu + 2H2SO4 —> CuSO4 + SO2 + 2H2O
(iii) It is a strong oxidizing agent and oxidizes as follows,
H2SO4 —> H2O + SO2 + O
C + 2H2SO4 —> 2SO + CO + 2H2O
S + 2H2SO4 —> 3SO2 + 2H2O
P4 + 10H2SO4 —> 4H2PO4 + 10SO2 + 4H2O
2HBr + H2SO4 —> Br2 + 2H4O + SO2
2HI + H2SO4 —> 2H2O + I2 + 2SO2
(iv) It reacts with number of salts. It liberates HCl from chlorides, H2S from sulfides, HNO3 from nitrates.
(v) It acts as a strong dehydrating agent, as it dehydrates, sugar to sugar charcoal (carbon), formic acid to CO+CO2, oxalic acid to CO+ and ethyl alcohol to ethylene.
(vi) It is also a good sulfonating agent and used for sulfonation of aromatic compounds. eg.,
BaCl2 + H2SO4 ——> BaSO4 + 2HCl
(white ppt)
Pb(NO3)2 + H2SO4 —> PbSO4 + 2HNO3
Conc. H2SO4 Conc. H2SO4
C12H22O11 ———————> 12C + 11H2O HCOOH ———————> CO + H2O
Uses : H2SO4 is used (i) in the preparation of fertilizers like (NH4)2SO4 and super phosphate of lime, (ii) in lead storage batteries (iii) in preparation of dyes, paints and explosives (iv) in textile and paper industry (v) for training of tanning (vi) as a dehydrating agent.
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