n = m/M = 21,3/71 = 0,3 moli Cl2
2Fe + 3Cl2 => 2FeCl3
2 moli Fe.......3 moli Cl2
x moli Fe....0,3 moli Cl2
x = 0,2 moli Fe
3 moli Cl2..........2×162,5g FeCl3
0,3 moli Cl2........x = 32,5g FeCl3(md)
ms = md+mH2O = 32,5+167,5 = 200g solutie
C = md/ms×100 = 32,5/200×100 = 16,25%