Question

0.1 m aq. solution of which of the given compounds will have highest freezing point? A. NaCl
B. MgCl2
C. Urea
D. K4[Fe(CN)6]​

Answer 1

Depression in Freezing Point:

• When aqueous solutions are prepared, the freezing point is depressed below 0°C.

The general expression is :

$\boxed{\Delta T = i \times k_{f} \times m}$

• 'i' is Van't Hoff Factor, k_(f) is depression constant and 'm' is molality.

Now, in all the above solutions, the value of 'm' and 'k_(f)' is equal.

$\boxed{\Delta T \propto \: i}$

• So, solution with least Van't Hoff Factor will have least depression of freezing point and hence highest freezing point.

Value of 'i' in the options are:

• NaCl = 2
• MgCl2 = 3
• Urea = 1
• K4[Fe(CN)6] = 5

So, urea will have highest freezing point.

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