Galena(PbS) and cerussite(PbCO3)are two ores of lead. A mining company is considering which of these two ores to use for the extraction of lead.
The equations for the reactions occurring are
process using galena:
2PbS+3O2 ---> 2PbO+2SO2
2PbO+C ----> 2Pb+CO2
Process using cerussite:
PbCO3--->PbO+CO2
2PbO+c--->2Pb+CO2
The company uses a sample of cerussite containing 500g of PbCO3
Calculate the maximum mass of lead that can be obtained from this sample of cerussite. (3 marks)
Mass of lead=.............................g
500/207+12+(16x3) = 1.87
1.87x207 = mass of lead from PbCO3 = 387.09 g
To calculate the maximum mass of lead that can be obtained from the sample of cerussite, we need to determine the limiting reactant in the process.
First, let's calculate the number of moles of PbCO3 in the sample:
Molar mass of PbCO3 = 207.2 g/mol + 12.01 g/mol + 3(16.00 g/mol) = 267.2 g/mol
Number of moles of PbCO3 = mass / molar mass = 500 g / 267.2 g/mol
Next, we need to calculate the number of moles of lead (Pb) that can be obtained from the PbCO3:
From the balanced equation, we see that one mole of PbCO3 produces one mole of Pb:
Number of moles of Pb = Number of moles of PbCO3
Finally, we can calculate the mass of lead (Pb) in grams:
Mass of lead = Number of moles of Pb x molar mass of Pb = Number of moles of Pb x 207.2 g/mol
Therefore, the maximum mass of lead that can be obtained from the sample of cerussite is:
Mass of lead = Number of moles of Pb x molar mass of Pb = (500 g / 267.2 g/mol) x 207.2 g/mol
Simplifying this equation will give us the final answer.
To calculate the maximum mass of lead that can be obtained from the sample of cerussite (PbCO3), we need to determine the stoichiometry of the reaction and use the given information.
Let's look at the balanced equation for the reaction between cerussite (PbCO3) and carbon (C):
PbCO3 --> PbO + CO2 (Equation 1)
From the equation, we can see that 1 mole of cerussite (PbCO3) produces 1 mole of lead oxide (PbO). Now we need to determine the molar mass of PbO.
The molar mass of PbO is calculated using the periodic table:
1 mole of lead (Pb) has a molar mass of approximately 207.2 g/mol.
1 mole of oxygen (O) has a molar mass of approximately 16.0 g/mol.
So, the molar mass of PbO would be:
(1 mole of Pb) + (1 mole of O) = 207.2 g/mol + 16.0 g/mol = 223.2 g/mol
Now, we can use this information to calculate the maximum mass of lead (Pb) from the given sample.
Given:
Mass of PbCO3 = 500 g
Molar mass of PbCO3 = 267.2 g/mol (calculated)
To find the maximum mass of lead (Pb) produced, we need to convert the mass of PbCO3 to moles using the molar mass.
Number of moles of PbCO3 = Mass of PbCO3 / Molar mass of PbCO3
Number of moles of PbCO3 = 500 g / 267.2 g/mol = 1.872 mol (approx)
From the stoichiometry of Equation 1, we can see that 1 mole of PbCO3 produces 1 mole of PbO.
Therefore, the number of moles of PbO produced would also be 1.872 mol.
Now, to calculate the mass of lead (Pb) produced, we need to convert the moles of PbO to grams using the molar mass of PbO.
Mass of Pb = Number of moles of PbO x Molar mass of PbO
Mass of Pb = 1.872 mol x 223.2 g/mol = 417.3824 g (approx)
Therefore, the maximum mass of lead that can be obtained from the sample of cerussite is approximately 417.4 g.
mols PbCO3 = grams/molar mass
Convert mols PbCO3 to mols PbO using the coefficients in the first balanced equation.
Convert mols PbO to mols Pb in the second balanced equation.
Now convert mols Pb to g Pb. g = mols x atomic mass.
You can do all of the conversions at once if you wish and save some time.
mols PbCO3 x (1 mol PbO/1 mol PbCO3) x (2 mol Pb/2 mols PbO) = ?
Then convert mols Pb to grams.