Question

Which of the following solutions has a highest melting point? A.   0.40 m KNO3    B.   0.20 m Ca(NO3)2     C.   0.10 m Al(NO3)3     D.   0.30 m C6H12O6    E.   0.10 m NaCl

Answer 1

A.

0.40 m KNO3 = 2 x 0.40 ions after dissociation = 0.80 m particles

B.

0.20 m Ca(NO3)2 = 3 x 0.20 = 0.60 m Particles after dissociation

C.

0.10 m Al(NO3)3 = 4 x 0.10 = 0.40 m Particles after dissociation

D.

0.30 m C6H12O6 = 0.30 m C6H12O6 , no dissociation as it is non electrolyte.

E.

0.10 m NaCl = 2 x 0.10 = 0.20 m Particles after dissociation.

Higher is the number of solute particles lower is the melting point.

Lower is the number of solute particles higher is the melting point.

Since, 0.10 m NaCl has the lowest number of solute particles, hence it has the highest melting point.

Therefore, the answer is,

(E) 0.10 m NaCl