Answer to Question #112943 in General Chemistry for Lauren Barad

Question

A 2.0m solution has a boiling point of 103.1oC. The Kb for water is 0.52oC/m, which of the following could be the solute?

b. KOH
c. CAF2
d. Al2O3

Answer 1

Boiling Point Elevation: A solution will boil at a higher temperature than the pure solvent. This is the colligative property called boiling point elevation. The more solute dissolved, the greater the effect. An equation has been developed for this behavior. It is: 

$\Delta Tb=i\times Kb\times m$

$103.1−100=i\times0.52\times2$

i=2.98 or 3

Dissociation constant = 3, 3 ions is released in solution, it is CaF₂

c.