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.
I didn't know if you meant to the power of 14 but if you did here your answer:
3.64 x 10^-19
(you just multiply the frequency by Planck's constant= 6.63 × 10^–34)