Question

What is the concentration of 0.4m FeCl3 in water,0.5m MgCl2 in water, and 0.5 MgSO4 in water? I was told that the greater the concentration the smaller the freezing point...Which solution has the greatest freezing point and which has. the lowest freezing point? Please show work.

Answer 1

We know that ΔTf = iKf x m
Where
ΔT f = depression in freezing point
= freezing point of pure solvent – freezing point of solution
K f = depression in freezing constant
i= vanthoff’s factor
m = molality of the solution

So the product of I & m is more then that solution has lower freezing point.

Solution. i* m value

0.4 m FeCl3 ----> 4*0.4=1.6

0.5 m MgCl2 ----> 3*0.5 = 1.5

0.5 m MgSO4. -----> 2*0.5 = 1.0

So 0.4 m FeCl3 has lowest freezing point.

0.5 m MgSO4 has highest freezing point