Question

Which aqueous solution will have the highest boiling point temperature? A. 0.100 molal NiBr2(aq) B. 0.250 molal CH3OH(aq) C. 0.100 molal MgSO4(aq) D. 0.150 molal Na2SO4(aq) E. 0.150 molal NH4NO3(aq)

Answer 1

Answer: 0.150 m $Na_2SO_4(aq)$ will have highest boiling point.

Explanation:

Formula used for Elevation in boiling point :

$\Delta T_b=i\times k_b\times m$

where

$\Delta T_b=T_b-T^o_b$= elevation in boiling point

[tex[k_b[/tex]  = boiling point constant  

m = molality

i = Van't Hoff factor

A) 0.100 m $NiBr_2$

i = 3 as $NiBr_2\rightarrrow Ni^{2+}+2Br^-$

concentration will be $3\times 0.100=0.300$

B) 0.250 m $CH_3OH$

i = 1 as $CH_3OH$ is a non electrolyte

concentration will be $1\times 0.250=0.250$

C) 0.100 molal $MgSO_4(aq)$

i = 2 as $MgSO_4\rightarrrow Mg^{2+}+SO_4^{2-}$

concentration will be $2\times 0.100=0.200$

D. 0.150 molal $Na_2SO_4(aq)$

i = 3 as $Na_2SO_4\rightarrrow 2Na^{+}+SO_4^{2-}$

concentration will be $3\times 0.150=0.450$

E. 0.150 molal $NH_4NO_3(aq)$

i = 2 as $NH_4NO_3\rightarrrow NH_4^{+}+NO_3^{-}$

concentration will be $2\times 0.150=0.300$

The solution having the highest concentration of ions will have the highest boiling point and thus 0.150 m $Na_2SO_4(aq)$ will have highest boiling point.