Answer:
- 0.99 °C ≅ - 1.0 °C.
Explanation:
ΔTf = (Kf)(m),
where, ΔTf is the depression in the freezing point.
Kf is the molal freezing point depression constant of water = -1.86 °C/m,
m is the molality of the solution (m = moles of solute / kg of solvent = (23.5 g / 180.156 g/mol)/(0.245 kg) = 0.53 m.
∴ ΔTf = (Kf)(m) = (-1.86 °C/m)(0.53 m) = - 0.99 °C ≅ - 1.0 °C.