Experiment_5_Freezing_Point_Depression

LAB 5

What is freezing-point depression?

The process in which adding a solute to a solvent decreases the freezing point of the solvent.

What examples illustrate freezing-point depression?

Salt in water, alcohol in water, mixing of solids such as impurities in powdered drugs.

Explain the significance of seawater in relation to freezing-point depression.

Seawater remains liquid below 0 °C due to the presence of salt and other dissolved substances.

What is the formula to calculate freezing point depression?

ΔT = (Kf)(msolution)(i)

What do the symbols in the freezing point depression equation represent?

ΔT: freezing point depression, Kf: molar freezing point constant, msolution: molality of particles, i: number of ions.

What does a 1:1 ratio for non-electrolytes indicate in freezing point depression?

The molality of the non-electrolyte is equal to the molality of the particles in solution.

How is the van’t Hoff factor related to electrolytes like NaCl?

For electrolytes, molality of particles is equal to the molality of the electrolyte multiplied by the number of ions.

What temperature should the ice-salt mixture reach in the experiment?

At or below -10°C.

What is the purpose of preparing an ice-water bath in the experiment?

To facilitate the freezing point measurement of the water and NaCl solution.

What is the boiling point of pure water?

0 °C (32 °F) is the freezing point of pure water.

How is the percent error calculated in the freezing point depression experiment?

|∆Tobservation - ∆Tcalculation| / ∆Tcalculation × 100%.

List a possible reason for error in measured ΔT results.

Inaccurate measurement of temperature or contamination of the solute.