Answer
is: the molar mass of a covalent compound is 90.4 g/mol.
m(compound) = 0.486 g.
m(water) = 25 mL · 1 g/mL = 25 g ÷ 1000 g/kg = 0.025 kg.
ΔT = 0°C - (-0.40°C) = 0.40°C.
Kf(H₂O) = 1.86°C/m.
M(compound) = Kf · m(compound) /
m(water) · ΔT.
M(compound)= 1.86°C/m · 0.486 g /
(0.025 kg · 0.4°C).
M(compound) = 90.4 g/mol.
