(a) Interpretation: The value of K f for cyclohexane should be determined. Concept introduction: Freezing point depression of a solvent occurs due to the addition of nonvolatile solute. The amount that the freezing point is lowered is proportional to the mole fraction of the solute. In dilute solutions, solute mole fraction is equal to its molality. The freezing point depression can be determined by Δ T f = − K f × m Δ T f - freezing point depression ( 0 C) K f - proportionality constant ( 0 C mol-1 kg) (depends on melting point, enthalpy of fusion, molar mass of the solvent) m − molality (mol/kg)
(a) Interpretation: The value of K f for cyclohexane should be determined. Concept introduction: Freezing point depression of a solvent occurs due to the addition of nonvolatile solute. The amount that the freezing point is lowered is proportional to the mole fraction of the solute. In dilute solutions, solute mole fraction is equal to its molality. The freezing point depression can be determined by Δ T f = − K f × m Δ T f - freezing point depression ( 0 C) K f - proportionality constant ( 0 C mol-1 kg) (depends on melting point, enthalpy of fusion, molar mass of the solvent) m − molality (mol/kg)
Solution Summary: The author explains that the value of K f for cyclohexane should be determined. Freezing point depression occurs due to the addition of nonvolatile solute.
The value of Kf for cyclohexane should be determined.
Concept introduction:
Freezing point depression of a solvent occurs due to the addition of nonvolatile solute. The amount that the freezing point is lowered is proportional to the mole fraction of the solute. In dilute solutions, solute mole fraction is equal to its molality. The freezing point depression can be determined by
ΔTf=−Kf×m
ΔTf - freezing point depression (0C)
Kf - proportionality constant ( 0C mol-1 kg) (depends on melting point, enthalpy of fusion, molar mass of the solvent)
m − molality (mol/kg)
Interpretation Introduction
(b)
Interpretation:
The better solvent for molar mass determinations by freezing point depression should be determined.
Concept introduction:
The freezing point depression can be used to determine molar mass of an unknown compound. The freezing point depression can be determined by
ΔTf=−Kf×m
ΔTf - freezing point depression (0C)
Kf - proportionality constant (0C mol-1 kg) (depends on melting point, enthalpy of fusion, molar mass of the solvent)
m − molality (mol/kg)
Kf indicates the extent of the depression of freezing point per 1 molal solution.
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.