I have a question that talks about van’t Hoff factors and then asks for the freezing point of a .5 molal solution in water. Can someone give me an idea of what a van’t Hoff factor is?
The Van’t Hoff factor is essentially a measure of how much a particular molecule breaks up. With respect to colligative properties, the Van’t Hoff factor is used to see how things like ionic solids change said properties. For example, water(when it’s an impurity in some other solvent) and other solids that do not break up upon solvation(such as glucose) have a Van’t Hoff factor of 1 since they do not break up. On the other hand, ionic solids like KBr or NaCl have a Van’t Hoff factor of 2 since they break up from a single molecule into two charged species. Hope that helps!
In a nutshell:
1 molecule before solvation -> 1 molecule after solvation -> Van’t Hoff =1
1 molecule before solvation -> 2 molecules after solvation -> Van’t Hoff =2
1 molecule before solvation -> 4 molecules after solvation -> Van’t Hoff =4
And so on.