Chemistry · Ch 7 — Elements of Groups 16, 17 and 18

Oxoacids of sulfur

7.8.1

Oxoacids of sulfur

Sulfur forms a number of oxoacids. Some of them are unstable and cannot be isolated; they are known to exist in aqueous solutions or in the form of their salts. Some important oxoacids of sulfur and their structures are given below.

i. Sulfurous acid, $\mathrm{H_2SO_3}$

Figure 7.8.1aStructural formula of sulfurous acid H2SO3: a central sulfur atom carrying one lone pair, one sulfur-oxygen double bond, and two S-OH groups.

Fig. 7.8.1a — Structural formula of sulfurous acid H2SO3: a central sulfur atom carrying one lone pair, one sulfur-oxygen double bond, and two S-OH groups.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Sulfurous acid, $\mathrm{H_2SO_3}$ . The central S carries one lone pair (the lobe with two dots), one S=O double bond, and two -OH groups - a pyramidal arrangement. The lone pair is why sulfurous acid's su …

ii. Sulfuric Acid, $\mathrm{H_2SO_4}$

Figure 7.8.1bStructural formula of sulfuric acid H2SO4: a central sulfur atom with two sulfur-oxygen double bonds and two S-OH groups, tetrahedral about sulfur.

Fig. 7.8.1b — Structural formula of sulfuric acid H2SO4: a central sulfur atom with two sulfur-oxygen double bonds and two S-OH groups, tetrahedral about sulfur.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Sulfuric Acid, $\mathrm{H_2SO_4}$ . Sulfur at its +6 state: two S=O double bonds and two -OH groups, with no lone pair left on S - the four oxygens use up all six valence electrons. This is the only oxoacid of the six that is manufactured and handled as the pure liquid; t …

iii. Di or pyrosulfuric acid, $\mathrm{H_2S_2O_7}$

Figure 7.8.1cStructural formula of pyrosulfuric (disulfuric) acid H2S2O7: two sulfur centres joined through a bridging oxygen, each sulfur carrying two double-bonded oxygens and one OH group.

Fig. 7.8.1c — Structural formula of pyrosulfuric (disulfuric) acid H2S2O7: two sulfur centres joined through a bridging oxygen, each sulfur carrying two double-bonded oxygens and one OH group.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Di or pyrosulfuric acid, $\mathrm{H_2S_2O_7}$ - two sulfuric-acid halves sharing one bridging O: each S keeps its two S=O bonds and one -OH. This is oleum's acid (7.10.2). *(In the book this structure sits at the very bottom of one page and its name-label "iii." prints at the top of the next - the cap …

iv. Peroxy monosulfuric acid, $\mathrm{H_2SO_5}$

Figure 7.8.1dStructural formula of peroxymonosulfuric acid H2SO5, Caro's acid: a sulfur centre with two double-bonded oxygens, one OH group and one hydroperoxy O-OH group written as HOO.

Fig. 7.8.1d — Structural formula of peroxymonosulfuric acid H2SO5, Caro's acid: a sulfur centre with two double-bonded oxygens, one OH group and one hydroperoxy O-OH group written as HOO.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Peroxy monosulfuric acid, $\mathrm{H_2SO_5}$ . Like sulfuric acid, but one -OH is replaced by a hydroperoxy group -O-OH (the "HOO-" in the drawing) - the peroxide linkage that …

v. Peroxy disulfuric acid, $\mathrm{H_2S_2O_8}$

Figure 7.8.1eStructural formula of peroxydisulfuric acid H2S2O8, Marshall's acid: two sulfur centres joined through an O-O peroxide bridge, each with two double-bonded oxygens and an OH group.

Fig. 7.8.1e — Structural formula of peroxydisulfuric acid H2S2O8, Marshall's acid: two sulfur centres joined through an O-O peroxide bridge, each with two double-bonded oxygens and an OH group.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Peroxy disulfuric acid, $\mathrm{H_2S_2O_8}$ (Marshall's acid). Two $\mathrm{-SO_2(OH)}$ units joined through an -O-O- peroxide bridge - compare pyrosulfuric acid above, whose two halves share only a single bridging O. It is the second of the two peroxy acids in this family, and like $\mathrm{H_2SO_5}$ it is …

vi. Thiosulfuric acid, $\mathrm{H_2S_2O_3}$

Figure 7.8.1fStructural formula of thiosulfuric acid H2S2O3: a central sulfur with a double-bonded terminal sulfur in place of one oxygen, one S=O bond and two OH groups.

Fig. 7.8.1f — Structural formula of thiosulfuric acid H2S2O3: a central sulfur with a double-bonded terminal sulfur in place of one oxygen, one S=O bond and two OH groups.

Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.

Thiosulfuric acid, $\mathrm{H_2S_2O_3}$ . Sulfuric acid with one of its double-bonded oxygens swapped for a terminal =S ("thio" = sulfur-for-oxygen). The central S keeps one S=O and the two -OH groups. Its sodium salt, the familiar 'hypo' of photography, is far more sta …

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