Question

Which solution will have a higher boiling point, and which will have a lower freezing point? Explain why. (A) 0.5 M AgNO3. (B) 0.5 M Al(NO3)3.

a) Solution A has a higher boiling point and a lower freezing point.
b) Solution B has a higher boiling point and a lower freezing point.
c) Solution A has a higher boiling point and a higher freezing point.
d) Solution B has a higher boiling point and a higher freezing point.

Answer 1

Solution B (0.5 M Al(NO3)3), which dissociates into more particles, will have both a higher boiling point and a lower freezing point than solution A (0.5 M AgNO3) due to greater effects on the colligative properties.

Step-by-step explanation:

To determine which solution will have a higher boiling point and which will have a lower freezing point, we must consider the effects of solute concentration on the colligative properties of the solutions. In general, the greater the concentration of particles in a solution, the higher the boiling point and the lower the freezing point, relative to the pure solvent. Since ionic compounds dissociate into ions, a solution with an ionic compound will have more particles compared to a solution with a molecular compound at the same molarity.

For solutions (A) 0.5 M AgNO3 and (B) 0.5 M Al(NO3)3, both being ionic compounds, the key is to identify how many particles each compound dissociates into. AgNO3 dissociates into 2 particles (Ag+ and NO3−), whereas Al(NO3)3 dissociates into 4 particles (Al3+ and 3 NO3−). Therefore, solution B will have more particles and will exhibit the greater colligative property effects.

The correct answer is b) Solution B has a higher boiling point and a lower freezing point.