ms=200g FeCl3
Cp=40%
Cm=2M
Cp=md/ms*100=> md=Cp*ms/100=40*200/100=80g
Cm=md/M*Vs => Vs=md/Cm*M=80/2*40=1L NaOH
MNaOH=23+16+1=40g/mol
FeCl3 + 3NaOH -> Fe(OH)3 + 3NaCl
MFeCl3=56+3*35.5=162.5g/mol
MFe(OH)3=56+3(16+1) = 107g/mol
162.5g FeCl3......107g Fe(OH)3
80g FeCl3.............xg Fe(OH)3
x=107*80/162.5=52.67g