MgCl2 + 2AgNO3 => Mg(NO3)2 + 2AgCl
95g MgCl2....................2×143,5g AgCl
xg MgCl2........................8,61g AgCl
x = 2,85g MgCl2
m H2O = 6,09-2,85 = 3,24g
95+18xg.................18xg H2O
6,09g...................3,24g
307,8= 51,3x
x = 6
F.M => MgCl2×6H2O