Question

Which has lowest freezing point at 1 atm?

1)0.1M NaCl solution

2)0.1M BaCl2 solution

3)0.1M sugar solution

4)0.1M FeCl3 solution

Answer 1

Sugar solution > NaCl solution > BaCl2 solution > FeCl3 solution
Fecl3 has the lowest freezing point.

Explanation :
FeCl3 produces more ions (four ions) on dilution therefore it has more colligative characteristics i.e depression in freezing point must be large. Colligative properties depend upon the number of ions produced on hydrolysis.

FeCl3 (aq) → Fe3+ + 3Cl-

Therefore depression in freezing point largely depends on the number of ions produced on dissociation.

Hence, depression in freezing point is minimum in such a compound which produces less ions or no ions.

Sugar is an organic compound therefore on hydrolysis, it produces no ions in the solution. Therefore, it has minimum depression in freezing point.

Hence, 0.1 (M) sugar solution has highest freezing point.