1. Oxoacids Learning Objectives Sulfuric acid: process and properties

2. Oxyacids of sulphur

3. Manufacture of Sulfuric Acid Solid sulfur, S(s), is burned in air to form sulfur dioxide gas, SO 2 S(s) + O 2 (g)  SO 2 (g) The mixture of sulfur dioxide and air is heated to 450 o C and subjected to a pressure of 1 -2 atm in the presence of a catalyst (vanadium (V) oxide) to produce sulfur trioxide, 2SO 2 (g) + O 2 (g)  2SO 3 (g) SO 3 is absorbed in 98% H 2 SO 4 to form oleum. SO 3 (g) + H 2 SO 4  H 2 S 2 O 7 There are two major processes used in the production of H 2 SO 4, lead chamber process and contact process. The lead-chamber process is the older of the two processes, and its product is aqueous sulfuric acid containing 62% to 78% H 2 SO 4.

4. Sulphuric Acid Pure sulfuric acid is a colourless, corrosive, oily liquid that boils(and decomposes) at about 300 o C. It has three very important properties: strong acid, dehydratig agent, oxidizing agent. Oleum on dilution with water gives desired concentration of HSO 4 H 2 S 2 O 7 (l) + H 2 O(l)  2H 2 SO 4 (l) The best way to dilute sulphuric acid is to carefully pour the acid into water with stirring

5. Flow diagram for the manufacture of sulphuric acid

6. Dehydrating Nature Concentrated acid (18M) is used as a dehydrating agent. e.g., sulfuric acid dehydrate sucrose, to produce a spongy mass of carbon. C 12 H 22 O 11 (s) + 11H 2 SO 4  12C(s) + 11H 2 SO 4.H 2 O

7. Oxidising Nature Oxidising power is intermediate between phosphoric and nitric acids. Both metals and non-metals are oxidised by concentrated sulfuric acid, which is reduced to SO 2. With Zn, the reduction of sulfuric acid goes further to give sulfur or H 2 S.

8. Uses of Sulfuric Acid Used in lead acid batteries, production of fertilizers (NH 4 ) 2 SO 4, superphosphate, Ca(H 2 PO 4 ) 2, to remove oxides from iron and steel before galvanising or electroplating, petrochemicals, dyestuffs, and detergents.. Used in the production of nitroglycerine, which is used as an explosive but can also be used as a vasodilator, a substance that dilates blood vessels and can be used in the treatment of certain types of heart disease.

9. Illustrative Problem A yellow powder is burnt in a stream of F 2 to obtain a colorless gas X which is thermally stable and has octahedral geometry. Another gas with same atoms as that of Y is obtained when SCl 2 is heated with NaF. What are X and Y? Solution :

10. Environmental Issues Smog consists mainly of particulate (ash and smoke), SO 2 and H 2 SO 4 mist. –Main contributor is the emission of SO 2. –Acid rain. –Levels of SO 2 and H 2 SO 4 above 0.10 ppm are considered potentially harmful. Especially to respiratory tract.