p% = puritatea = mpx100/mip
=> mp = mipxp%/100 = 190,9 x 88/100= 168 g Fe pur
168 g ...................... m g
2Fe + 3Cl2 => 2FeCl3
2x56........................ 2x(56+35,5x3)
=> m = 168x2x162,5/2x56 = 487,5 g FeCl3
niu = masa subst. / M.moleculara subst.
=> niu = 487,5 / 162,5 = 3 moli FeCl3