Question

I don't understand the Van't Hoff factor..
I feel dumb because I don't understand it

Answer 1

In essence, it accounts for the number of particles that can occur in "ideal" solutions. The typical definition is that it is the ratio of the actual concentration of particles in solution to the concentration of the solute as calculated by its mass.

So for non-ionic compounds in solution, like glucose (C6H12O6) , the van't Hoff factor is 1.

For ions with a one to one ratio, like NaCl, this dissociates into ions of Na+1 and Cl-1 and the van't Hoff factor is then 2.

For other ions it follows suit, so Magnesium Chloride MgCl2 dissociates to Mg2+, Cl-1, and another Cl-1 for an ideal van't Hoff factor of 3.

For something like Calcium Phosphate, Ca3(PO4)2 you would have 3 Ca2+ and 2 PO43- for a van't Hoff factor of 5. Using this example, you can see that for every 1 mole of Calcium Phosphate you have 3 moles of Calcium ions and 2 moles of Phosphate ions. Theoretically 5 moles of ions for every one mole of compound we dissolve in solution.

The reason I used "ideal" when describing those examples is because it relies on the assumption of total dissociation in order to hold true. The real scenario is going to have pairs of ions that will form in solution so that the actual ratio observed is less than the theoretical ratio we calculate.