Question

Which has the highest boiling point?

• A. $0.1 \,m\, Na_{2}SO_{4}$
• B. $0.1\,m\,Al(NO_{3})_{3}$
• C. $0.1\,m\,MgCl_{2}$
• D. $0.1\,m\,C_{6}H_{2}O_{6}$ (glucose)

Answer 1

Answer: (B)

$T_{b}$ (boiling point) $=T_{0}$ (Solvent) $+ \,\Delta \,T_{b}$
$\Delta\,T_{b}=m\times K_{b} \times i$
m (same) = 0.1 molal $\Delta T_{b} \propto\,i$
Greater the value of i, larger the boiling point of solution
(a) $Na_{2}SO_{4} \rightleftharpoons 2Na^{+}+SO^{2-}_{4}, 3$
(b) $C_{6}H_{12}O_{6}$ (non-electrolyte), 1
(c) $MgCl_{2} \rightleftharpoons Mg^{2+}+2Cl^{-}, 3$
(d) $Al(NO_{3})_{3} \rightleftharpoons Al^{3+}+3NO^{-}_{3}, 4$