Got a Chemistry Stoichiometry Problem.. Please Help!

Question

Question: The final step in manufacture of pure platinum (for use in automobile catalytic converters and other purposes) is the decomposition reaction of (NH4)2PtCl6. In addition to the solid metal, the following gaseous byproducts are also formed: ammonium chloride, nitrogen, and hydrogen chloride. If 6.2g of platinum is desired, but the reaction gives only an 85% yield, how many grams of (NH4)2PtCl6 are required?

Answer 1

3(NH4)2PtCl6 ==> 3Pt(s) + 2NH4Cl + 2N2 + 16HCl  balanced equation for decomposition

moles of Pt desired = 6.2 g x 1 mole/195 g = 0.032 moles

moles (NH4)2PtCl6 needed = 0.032 moles Pt x 3 moles (NH4)2PtCl6/3 mole Pt = 0.032 moles (NH4)2PtCl6 needed

mass (NH4)2PtCl6 needed = 0.032 moles x 444 g/mole = 14.2 g needed

At 85% yield, mass (NH4)2PtCl6 needed = 14.2 g/0.85 = 16.7 g = 17 g (to 2 significant figures)