Answer:

Therefore, the freezing point of the trichothecin solution is 2.61 °C.

Explanation:

First, we need to calculate the molality of the trichothecin solution:

Molar mass of trichothecin (C19H2405) = 332.37 g/mol

Number of moles of trichothecin = 140 g / 332.37 g/mol = 0.421 mol

Mass of benzene = 0.746 kg = 746 g

Molality (m) = moles of solute / mass of solvent (in kg)

m = 0.421 mol / 0.746 kg = 0.564 mol/kg

Next, we can use the freezing point depression equation:

ΔTf = Kf × m

where ΔTf is the change in freezing point, Kf is the freezing point depression constant, and m is the molality of the solution.

Substituting the given values:

ΔTf = 5.12 °C/m × 0.564 mol/kg = 2.89 °C

Finally, we can calculate the freezing point of the solution:

Freezing point = Freezing point of pure solvent - ΔTf

Freezing point = 5.5 °C - 2.89 °C = 2.61 °C