The basis for the freezing point osmometer is which statement?

The basis for the freezing point osmometer is which statement?

• A. The freezing point depression is directly proportional to the amount of solvent present.
• B. The freezing point depression varies as the logarithm of the concentration of solute.
• C. The freezing point is raised by an amount that is inversely proportional to the concentration of dissolved particles in the solution.
• D. The freezing point is lowered by an amount that is directly proportional to the concentration of dissolved particles in the solution.

Answer: (D)

The main idea is that freezing point depression is a colligative property: it depends on the amount of dissolved particles, not on their identity. In an osmometer, more dissolved particles lower the freezing point further because each particle disrupts the formation of the solid ice lattice. This relationship is captured by the equation ΔTf = i · Kf · m (or its osmolality equivalent), which shows the freezing point is lowered in direct proportion to the concentration of dissolved particles. So the statement that the freezing point is lowered by an amount directly proportional to the concentration of dissolved particles is the correct basis. The other options describe effects that don’t match how freezing point depression behaves: it’s not about the solvent amount alone, not a logarithmic relationship, and it’s not a raise in freezing point or an inverse dependence.

The main idea is that freezing point depression is a colligative property: it depends on the amount of dissolved particles, not on their identity. In an osmometer, more dissolved particles lower the freezing point further because each particle disrupts the formation of the solid ice lattice. This relationship is captured by the equation ΔTf = i · Kf · m (or its osmolality equivalent), which shows the freezing point is lowered in direct proportion to the concentration of dissolved particles. So the statement that the freezing point is lowered by an amount directly proportional to the concentration of dissolved particles is the correct basis. The other options describe effects that don’t match how freezing point depression behaves: it’s not about the solvent amount alone, not a logarithmic relationship, and it’s not a raise in freezing point or an inverse dependence.