question_answer

  An ore on treatment with dilute hydrochloric acid gives a smell like that of rotten eggs. What type of ore is this? How can it be concentrated? How can the metal be obtained from the concentrated ore?  

Answer:

                  The gas which smells like that of rotten eggs is H2S. Hence, the ore is a sulphide ore. It is concentrated by froth-floatation process. The metal is obtained from the concentrated ore in the following two steps: (i) Roasting: Heating the ore strongly in the presence of air. The metal sulphide is converted into metal oxide along with evolution of sulphur dioxide gas. Metal sulphide + O2    Metal oxide + SO2 (ii) Reduction with carbon; On heating the metal oxide with carbon, it is reduced to free metal. Metal oxide + CarbonMetal + Carbon monoxide