Question

Lead can be prepared from galena [lead (II) sulfide] by first roasting the galena in oxygen gas to form lead(II) oxide and sulfur dioxide. Heating the metal oxide with more galena forms the molten metal and more sulfur dioxide. a) Write a balanced equation for each step, including the state of each chemical. (1) (2) b) Write an overall balanced equation for the process, including the state of each chemical. (c)How many metric tons of sulfur dioxide form every metric ton of lead obtained.

Answer 1

2PbS(s) + 3O2(g) -----> 2PbO(s) + 2SO2(g) (Balanced reaction for the first case)

PbS(s) + O2(g) -----> Pb(l) + SO2(g) (Balanced reaction forming molten metal)

In both the reaction, one mole of PbS will give one mole of SO2

Molar mass of Pb = 207.2 gm/mol

Number of moles of PbS = 1000 * 10^(3)/239.2 = 4180.60 moles

Moles of SO2 formed = 4180.60 moles

Molar mass of SO2 = 32 + 2 * 16 = 64 gm/mol

Mass of SO2 formed = 4180.60 moles * 64 gm/mol = 0.26755 metric tonnes