posted by Angel on .
Solutions are made that contain 0.1 moles of each of the following compounds below in 100 g of H2O. Choose the compound whose solution will have the lowest freezing point.
I know the answer is MgCl2
but I don't know how to get it. I know I have to use a periodic table but don't see the solution please explain
The secret is remembering a little emphasized point when these problems are worked. That point is---"the extent to which these thing happen depends SOLELY on the number of dissolved particles."
So how many particles do we get when NaCl dissolves.
NaCl ==> Na^+ + Cl^- = 2.
MgCl2 ==> Mg^+2 + 2Cl^- = 3
KClO3 ==> K^+ + ClO3^- = 2
CO2 ==> doesn't dissolve to an appreciable extent and what little dissolves doesn't produce many ions so let's call this zero.
MgSO4 ==> Mg^+2 + SO4^-2 = 2
So which one produces the largest number of particles (all of them are the same molality). That would be MgCl2.