If we are given a compound,say BaCl2, how can we find the value of 'i' by observing the chemical formula alone?

Dear Susan,

 

BaCl₂ is strong elexctrolyte. The dissociation reaction for BaCl₂ is as follows:

BaCl₂ → Ba²⁺ + 2Cl^-

There are 3 ions. Hence the van't hoff factor or "i" for BaCl₂ is 3.