For 1 molal aqueous solution of the following compounds, which one will show the highest freezing point ?

 Answer: For 1 molal aqueous solution, the highest freezing point will be shown by (3) [Co(H₂O)₃Cl₃].₃H₂O 

[Co(H₂O)₅Cl]Cl₂.H₂O     i = 3
[Co(H₂O)₆Cl₂]Cl.₂H₂O    i = 2
[Co(H₂O)₃Cl₃].₃H₂O        i = 1
[Co(H₂O)₆]Cl₃                  i = 4
ΔT_f  ∝  i where ΔT_f  = (T_f – T_f^')
T_f' = F.P. of solution ,Freezing point of solution as ↑ as i↓

Remember: Van’t  Hoff factor is denoted by i.  

i = normal molecular mass/ observed molecular mass  

= observed colligative property/expected colligative property  

= actual number of particles/expected number of species. 

How to find the value of i while finding the highest freezing point in 1 molal solution