Help with chemistry question please.?

Question

Unknown solid containing Pb2+ was mixed with 12ml 2.0M HCL. The mixture bubbled profusely. 0.020 mols CO2 was produced. What is the chemical formula of the unknown solid? Calculate the mass of the original unknown solid.

Answer 1

The equation is PbCO3+2HCl--> PbCl2+CO2+H2O

0.020moles CO2 was produced  

12ml of 2.0 M HCl  correspond to 12*2*10^-3= 0.024 mole HCl.

So the solid contained only 20/24 = 83.3% = 0.83 of PbCO3, other being water.

The mass of PbCO3 = 207+12+3*16=267

the mass of water is 267*16.7/83.3=53.4 corresponding to 3 moles H

so PbCO3, 3H2O

Answer 2

Good Answer!