Questions: Which statement explains the difference in expected versus actual boiling temperature?

Solution Steps

Boiling point elevation is a colligative property, which means it depends on the number of solute particles in a solution, not their identity. The formula for boiling point elevation is:

\[ \Delta T_b = i \cdot K_b \cdot m \]

where:

• \(\Delta T_b\) is the boiling point elevation,
• \(i\) is the van't Hoff factor (number of particles the solute dissociates into),
• \(K_b\) is the ebullioscopic constant of the solvent,
• \(m\) is the molality of the solution.

1. The molecules dissociate a small amount because it is a weak acid.

   • Weak acids partially dissociate in solution, which means the actual number of particles is less than if the acid dissociated completely. This would result in a lower than expected boiling point elevation.

2. The molality of the solution is actually higher than 0.1.

   • If the molality is higher than expected, the boiling point elevation would be greater than calculated, leading to a higher actual boiling temperature.

3. The molecules dissociate entirely into three separate particles.

   • If the molecules dissociate completely into three particles, the van't Hoff factor \(i\) would be 3, leading to a higher boiling point elevation than expected if the dissociation was not considered.

The question asks for the difference between expected and actual boiling temperature. If the actual boiling temperature is higher than expected, it could be due to either a higher molality or complete dissociation into more particles than anticipated.

Final Answer