Question

Which of these solutes raises the boiling point of water the most?

Answer 1

I think the answer would be Ionic sodium phosphate (Na3PO4) because it has the greatest boiling point elevation.

Answer 2

Answer: ionic sodium phosphate $(Na_3PO_4)$

Explanation:

The formula used:

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

$\Delta T_b$= change in boiling point

i = Van'T Hoff factor  

$k_b$ = boiling point constant

m = molality

1.  For $LiCl$

$LiCl\rightarrow Li^{+}+Cl^{-}$  

i= 2 as it is ionic and dissociate to give 2 ions.

2. For $NaCl$

$NaCl\rightarrow Na^{+}+Cl^{-}$  

i= 2 as it is ionic and dissociate to give 2 ions.

3. For $C_{12}H_{22}O_{11}$

, i= 1 as it is a non electrolyte and does not dissociate.

4. For $Na_3PO_{4}$

$Na_3PO_4\rightarrow 3Na^{+}+PO_4^{3-}$  

, i= 4 as it is ionic and dissociate to give 4 ions.

5.  For $MgBr_{2}$

$MgBr_2\rightarrow Mg^{2+}+2Br^-$  

, i= 3 as it is ionic and dissociate to give 3 ions.

Thus as vant hoff factor is highest for $Na_3PO_{4}$ , the boiling point will be raised most.