Answer:
2FeCl3 + 3Na2S --> Fe2S3 + 6NaCl
moles of Fe2S3 = 0.690 g / 207.9 g/mole = 0.00332 mole
0.00332 mole = X mole x 65.0%
X mole = 0.00511 mole (at 100% yield)
You require 2 mole FeCl3 to produce 1 mole of Fe2S3 (at 100% yield)
moles of FeCl3 = 0.00511 x 2 = 0.0102 mole
0.0102 mole = 0.200 mole/liter x liters of FeCl3
liters of FeCl3 = 0.0511 (51.1 mL)
ANSWER: 51.1 mL