Its general formula is BaTi(SiO3)3.If a 15-carat stone were pure BaTi(SiO3)3, how many moles of silicon would it contain? (There are exactly 5 carats per gram.)

Answer 1

15 carats x (1 g/5 carats) = ? grams BaTi(SiO3)3.
mols BaTi(SiO3)3 = grams/molar mass + xx.
There are 3 Si mols/1 mol BaTi(SiO3)3; therefore, there must be 3* mols BaTi(SiO3)3 = mools Si atoms.