Gravimetric Analysis help

I need help with gravimetric analysis! So I need to find the identity of a Group 1 Metal carbonate by gravimetric analysis. A solution of calcium chloride was added to the carbonate solution to precipitate the carbonate ions as calcium carbonate.

The moles of CaCO3 are equal to the group 1 metal carbonate, M2CO3 (M being the metal)Dividing the mass of the unknown carbonate by the moles of calcium carbonate yields the formula weight, and thus the identity.

So the mass of the unknown carbonate in my lab was 2.00g
the mass of CaCO3 was 1.57 ---> in moles it would be 0.0157 moles

So then would I just do 2.00g Unknown/0.0157 CaCO3 moles?

And get 127.29 g M2CO3?

What do I do now? Or am I already doing it wrong?

Thank you!

u r right and I will show u

mole = mass / molar mass ...........or molar mass = mass /moles
CaCO3 moles = 1.57 g/ 100.08 = 0.0157 moles
CaCO3 mols = moles of unknown carbonat
molar mass of unknown = mass /moles = 2 / 0.0157 = 127.39 g/mol
CO3 molar mass = 12 + 3*16 = 60 g/mol
molar mass of the metal = 127.39 - 60 = 67.39 g/mol
from periodic table u can know what metal is