The rock in a lead ore deposit contains 84% PbS by mass. How many kilograms of the rock must a mining company process to obtain 1.0 kg of Pb?
Here, we are going to calculate the mass of rock required by the mining company to obtain 1.0 kg of Pb.
Molar mass of PbS = atomic mass of Pb + atomic mass of S
= 207.2 + 32.065
= 239.265 g/mol
Now, mass percentage of Pb in PbS = (207.2 / 239.265) x 100
= 86.6 %
I.e., in one kg of PbS, (86.6/100 = 0.866) kg of Pb is present.