Question

As a purchasing agent for a pharmaceutical company, how much chlorine, Cl2, do you need to order to react completely with 500 kg of platinum, Pt, to make cisplatin, PtCl2(NH3)2?

Answer 1

The formula tells you the proportion in mols

2 mols of Cl: 1 mol of Pt

Now use the atomic masses:

Cl: 35.5 g/mol
Pt: 195 g/mol

Then you have these equation:

[2*35.5 g Cl] / 195 g Pt = x / 500 kg Pt

Solve for x.

x = (71 g Cl / 195 g Pt) * 500 kg Pt

x = 182 Kg Cl = 182 kg Cl2.