An ore of lead contains 70% of PbS. Calculate the mass of lead that can be extracted from 478kg of the ore.
[Ar : Pb = 207; S = 32]
Answer:
22) D
Mass of PbS in 478kg of ore = 70% of 478 = 0.7 x 478 = 334.6kg ā 335 kg
Mr of PbS = 207 + 32 = 239
n = 335/239 ā 336/240 = 1.4 moles
Moles of Pb = 1.4 moles
n = m/Mr
m = n x Mr
m = 1.4 x 207 = 289.8
Hence D is the answer.
