Which statement correctly describes a colligative property?

Which statement correctly describes a colligative property?

• A. They depend on the temperature of the solvent.
• B. They depend on the mass of the solute.
• C. They depend on the identity of the solute particles.
• D. They depend on the number of solute particles.

Answer: (D)

Colloidative properties are set by how many solute particles are present in a solution, not by what the particles are. The more particles you have, the stronger the effect on properties such as boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. For electrolytes, the count can increase because compounds dissociate into ions, so the effective number of particles is the dissociation factor times the amount dissolved. That’s why describing them as depending on the number of solute particles is the best answer. The solvent’s temperature doesn’t define the effect, even though temperature affects the actual values observed. The mass of the solute isn’t the determining factor, since two solutes with the same particle count produce the same colligative effect regardless of their mass. And the identity of the solute doesn’t matter for ideal colligative behavior—the same number of particles yields the same impact, aside from effects due to dissociation for electrolytes.

Colloidative properties are set by how many solute particles are present in a solution, not by what the particles are. The more particles you have, the stronger the effect on properties such as boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. For electrolytes, the count can increase because compounds dissociate into ions, so the effective number of particles is the dissociation factor times the amount dissolved.

That’s why describing them as depending on the number of solute particles is the best answer. The solvent’s temperature doesn’t define the effect, even though temperature affects the actual values observed. The mass of the solute isn’t the determining factor, since two solutes with the same particle count produce the same colligative effect regardless of their mass. And the identity of the solute doesn’t matter for ideal colligative behavior—the same number of particles yields the same impact, aside from effects due to dissociation for electrolytes.