Question

Which of the following solutions will have the highest boiling point?
A. 0.1 M $FeC{l}_3$
B. 0.1 M $BaC{l}_2$
C. 0.1 M NaCl
D. 0.1 M Urea

Answer 1

Hint: The boiling point elevation is dependent on the concentration of solute in the solution. In the given compounds the concentration is the same. The boiling point elevation is a colligative property and it is related with the number of ions liberated during dissolution.

Complete step by step answer:
The boiling point elevation is defined as the increase in boiling point of solvent when another compound say solute is added to the solvent which means the boiling point of solution will be greater than the solvent.
The boiling point elevation is a colligative property which depends on the ratio of solute and solvent nut does not depend on the nature of solute which means the boiling point elevation is dependent on the quantity of solute added. When the concentration of solute in the solution of molarity is greater than the boiling point of the solution is high.
In the given solutions, the molarity of all the solutions is the same.
Here, the boiling point elevation depends on the number of ions dissociated by the compounds.
The dissociation of $FeC{l}_3$ is shown below.
$FeC{l}_3\to F{e}^{3+}+3C{l}^{-}$
The number of ions dissociated is 4.
The dissociation of $BaC{l}_2$ is shown below.
$BaC{l}_2\to B{a}^{2+}+2C{l}^{-}$
The number of ions dissociated is 3.
The dissociation of NaCl is shown below.
$NaCl\to N{a}^{+}+C{l}^{-}$
The number of ions dissociated is 2.
Urea does not give a dissociation reaction.
The maximum number of ions are present in 0.1 M $FeC{l}_3$.
Thus, 0.1 M $FeC{l}_3$ will have the highest boiling point.
So, the correct answer is “Option A”.

Note:
Urea is not an ionic compound, it is a covalent compound. Urea does not easily dissolve in water, a very high amount of energy is required to break the bond in urea.