Example 4.1). 7. The metals industry was a major source of air pollution years ago. One common process involved "roasting" metal sulfides in the air: 2PbS(s)+3O2(g)2PbO(s)+2SO2(g) If 2.50mol of PbS is heated in air, what amount of O2 is required for complete reaction? What amounts of PbO and SO2 are expected