Answer:
The freezing point for the solution is -64.09°C
Step-by-step explanation:
This problem can be solved, by the freezing point depression. This colligative problem shows, that the freezing point of a solution is lower than the freezing point of pure solvent.
ΔT = Kf. m
ΔT = T° freezing pure solvent - T° freezing solution
Kf = Cryscopic constant, for chloroform is 4.68
T°freezing pure solvent = -63.5°C
m is mol/kg of solvent → molality
Let's determine the moles of benzene
1.25 g / 78 g/mol = 0.0160 mol
Let's convert the mass of solvent to kg
125 g . 1kg / 1000 g = 0.125 kg
m = 0.0160 mol / 0.125 kg → 0.128 m
Let's go to the formula to replace the data
-63.5°C - T° freezing solution = 4.68 °C/m . 0.128 m
T° freezing solution = - (4.68 °C/m . 0.128 m + 63.5°C)
T° freezing solution = - 64.09°C