Answer:
a. Boiling point: MgF₂ will have the higher boiling point.
b. Vapor pressure: NaCl will have the higher vapor pressure.
c. Freezing point: NaCl will have the higher freezing point.
Step-by-step explanation:
- This is the change in the collegative properties of water by adding a solute particles.
- The addition of solute to water cause elevation of boiling water and depression of vapor pressure and freezing point.
- The no. of ions of the dissolved solute in the solution have a great effect on the collegative properties of water, what is known as van 't Hoff factor.
- The van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass.
- For most ionic compounds dissolved in water, the van 't Hoff factor is equal to the number of discrete ions in a formula unit of the substance. This is true for ideal solutions only, as occasionally ion pairing occurs in solution.
MgF₂ will be ionized into 3 ions (1 of Mg²⁺, 2 of F⁻) while NaCl will be ionized into 2 ions (1 of Na⁺, 1 of Cl⁻).
So, MF₂ will cause elevation of boiling point, depression in vapor pressure, and depression of freezing point higher than the effect of NaCl.
Thus:
a. Boiling point: MgF₂ will have the higher boiling point.
b. Vapor pressure: NaCl will have the higher vapor pressure.
c. Freezing point: NaCl will have the higher freezing point.