A mixture of powdered carbon and an oxide of lead was heated producing lead metal and carbon dioxide.when 13.70g of the lead oxide was reduced to lead by carbon,960cm^3 of carbon dioxide measured at r.t.p was formed.

Question

Calculate the empirical formular of the lead oxide???

Answer 1

There may be shorter ways to do this but here is what I would do.
PbxOy + C ==> yCO2 + xPb
Use PV = nRT and solve for mols CO2 at rtp.
Convert mols CO2 to g oxygen.
g Pb = 13.70-g O = g Pb

Then mols Pb = grams pb/atomic mass Pb = ?
mols O atoms = grams O/atomc mass O = ?

Now find the ratio of the elements to each other with the smallest number being no less than 1.00. The easy way to do that is to divide both numbers by the smaller number of mols. That way you get 1.00 for the smallest ratio. Then round to whole numbers but be careful that you don't get heavy handed in rounding; i.e., it's ok to round 1.9 to 2 and 2.1 to 2 but not to round 1.4 to 1 or 1.6 to 2. If you get a number like that, then multiply both small numbers by 2, then 3, then 4, then 5, etc until you get numbers close enough to whole numbers that they can be rounded. That will be the empirical formula. Post your work if you get stuck and I can help you through it.