Question

CaCl2 ---> Ca2+ + 2 Cl-

i'm trying to figure out the van't hoff factor. i know i=3.

But where did the 2 come from before Cl-.

Answer 1

That's the charge on the Ca ion.
CaCl2 ==> Ca⁺² + 2Cl^-. And your are correct that i=3. 1 for the Ca ion and 2 more for the Cl^- to make 3.