M,NiCl2= 130g/mol
niu,=m/M=156/130mol=1,2molNiCl2
diferenta (285,6-156)g= 129,6g repreainta masa de apa care se adauga sarii anhidre,pentru a forma cristalohidratul NiCl2.xH2O
M,H20=18g/mol
niu,apa=x= 129,6/18mol=7,2mol apa
1,2mol NiCl2...........7,2mol apa
1mol..........................x=6........................................NiCl2.6H2O