How many grams of barium chloride are needed to make 100. grams of barium sulfate?

Answer 1

The balanced equation is
BaCl2 + SO42- >> BaSO4 + 2 Cl-
mw of BaSO4 = 233 g/mol
100 g / 233 = 0.429 moles BaSO4

Since the ratio between BaCl2 and BaSO4 is 1 : 1 we need 0.429 moles BaCl2
mw of BaCl2 = 208.2 g/mol
0.429 mol x 208.2 g/mol = 89.3 g of BaCl2 needed

Answer 2

You need to use a periodic table to look up the molar mass of each element in the reactant and product.

1) BaSO4 = Ba + S + 4 x O gives you the mass of the BaSO4

2) Divide 100. g by the mass total you got above. That will give you the moles of BaSO4 produced.

3) BaCl2 = Ba + 2 x Cl gives you the mass of BaCl2

4) Multiply the answer from #2 by the answer from #3 to find the mass of BaCl2 required.