A solution containing 0.100 mol of Na2CO3 and 0.100 mol of NiCl2 is allowed to react. What mass of precipitate forms in this reaction?

Question

I think I know how to do it but don't understand. Do I figure out the mass of each of the compounds? HELP please!!!

Answer 1

This is a limiting reagent problem I know that because amounts for BOTH reactants are given.
I do these the long way but I think that is easier. Write and balance the equation.
Convert 0.l00 mol Na2CO3 to NiCO3(the ppt) assuming you have all of the NiCl2 needed.
Then convert 0.100 mol NiCl2 to NiCO3 assuming you have all of the Na2CO3 needed.
These numbers won't agree; the correct one is ALWAYS the smaller value. That will be the mole NiCO3 formed and the reagent producing that number is the limiting reagent. The other reagent will use whatever is needed and there will be some that is unreacted.

Answer 2

Then mols is converted to grams. g = mols x molar mass.