We’re being asked to rank the given solutions in order of increasing vapor pressure and determine the 4th on the list
The vapor pressure of a solution is related to the intermolecular forces: a stronger IMF leads to lower vapor pressure. This means the solution with the lowest vapor pressure has the strongest IMF, and vice-versa.
Recall that a solution with higher solute concentration will have a stronger IMF, resulting in lower vapor pressure. Therefore, we need to calculate the osmolality of each solution, which is given by:
where i = van’t Hoff factor.
When the following aqueous solutions are ranked in order of INCREASING vapor pressure, which solution is fourth on the list (lowest vapor pressure)?
a. 0.2 m KNO3
b. 0.2 m urea, (NH2)2CO
c. 0.1 m CaCl2
d. 0.1 m glucose, (C6H12O6)