Question

Identify the compound amongst the following of which 0.1 M aqueous solution has highest boiling point.
(A.) Glucose.
(B.) Sodium chloride.
(C.) Calcium chloride.
(D.) Ferric chloride.

Answer 1

Glucose.... I'm not sure about this....

Answer 2

Answer: (D.) Ferric chloride.

Explanation:

Elevation in boiling point:

$\Delta T_b=i\times K_b\times \frac{\text{mass of glycerol}}{\text{molar mass of glycerol}\times \text{weight of solvent in kg}}$

$\Delta T_b$ = change in boiling point

i= vant hoff factor = no of ions produced on complete dissociation of an electrolyte

$K_b$ = boiling point constant

A) Glucose: i= 1 as it is a non electrolyte and does not dissociate.

B) Sodium chloride :$NaCl$

$NaCl\rightarrow Na^++Cl^-$

i= 2

C) Calcium chloride  :$CaCl_2$

$CaCl_2\rightarrow Ca^{2+}+2Cl^-$

i= 3

D) Ferric chloride : $FeCl_3$

$FeCl_3\rightarrow Fe^{3+}+3Cl^-$

i= 4

Thus as molarity and boiling point constant is same for all electrolytes, when i=4, elevation in boiling point will be highest.