Hey MiG,
I took Chemistry last year, so I might have forgotten some stuff, but let me try and help you.
1) Convert 250 ml to L; It will be 0.25 L
2) Molarity is mol of solute / L of solution, so write that out.
3) There are 3 Cl- required to make FeCl3, so 3 mol of Cl- is 1 mol of FeCl3
4) Use the period table to find the mass of FeCl3, and write that out.
5) Multiply and find your answer.
0.25 L FeCl3 0.25 mol Cl- 1 mol FeCl3 162.35 g FeCl3
x --------------- x ---------------- x --------------------- = 3.3823 g FeCl3
1 L FeCl3 3 mol Cl- 1 mol FeCl3