Lead 2 sulfide is the principle source of lead metal. To obtain the metal the sulfide is first heated in air to produce PbO.
PbS+3/2O2=PbO+ SO2 H=- 415.4 kj
the oxide is then reduce to the metal with carbon. PbO + C= Pb + CO H=108.5 KJ
Calculate H for the reaction of one mole of PbS with Oxygen and carbon, forming lead, sulfur dioxide and carbon monoxide.