What is the new freezing point for a 0.811m solution of Li2O in water?

Freezing T° of solution = - 4.52°C

Explanation:

ΔT = Kf . m . i

That's the formula for colligative property about freezing point depression.

Li₂O is an oxide that can not be dissociated but, if we see it's a ionic compound.

Li₂O →  2Li⁺  +  O⁻²

3 moles of ions have been formed. Ions dissolved in solution are i, what we call Van't Hoff factor.

m is molality → 0.811 m, this is data

Kf →Cryoscopic constant, for water is 1.86 °C/m

and ΔT = Freezing T° of pure solvent - Freezing T° of solution

We replace: 0°C - Freezing T° of solution = 1.86°C/m . 0.811 m . 3

Freezing T° of solution = - 4.52°C