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Question

Dont knwo how to set this problem up

Lead is often found in Earth's crust as several lead compounds called lead ores. Calculate the mass in kilograms of the amount of each of the following lead compounds that contains 6.0 103 kg of lead.
(a) PbS (galena)
kg
(b) PbCO3 (cerussite)
kg
(c) PbSO4 (anglesite)
kg

Answer 1

The key here is to convert to moles.

Step 1: Find the molar mass of lead, then find how many moles are in 6.0103 kg of lead.
Molar mass of lead - 207.2 Moles/kg.
6.0103 kg * 1/207.2 kg/mole = 0.029 moles

Step 2: Find the molar mass of each compound, then determine how many moles of Pb are in each compound.
PbS - 207.2 + 32.065 = 239.265 kg/mol, 1 mol Pb.
PbCO3 - 207.2 + 12 + 3 * 16 = 267.2 kg/mol, 1 mol Pb
PbSO4 - 207.2 + 32.065 + 16 * 4 = 303.265 kg/mol, 1 mol Pb

Step 3: Now that you have the molar mass of each compound, and you've found that there's 1 mole Pb per mole of compound, multiply the number of moles by the molar mass.

a.) PbS - 239.265 kg/mol * 0.029 moles = 6.939 kg
b.) PbCO3 - 267.2 kg/mol * 0.029 moles = 7.749 kg
c.) PbSO4 - 303.265 kg/mol * 0.029 moles = 8.795 kg

Answer 2

Very interesting.