Question

Explain very clearly why a mole of hydrogen chloride depresses the freezing point of 1.0kg of water by almost twice as much as a mole of ethanol.

Answer 1

It's the van't Hoff factor.
For ethanol,
delta T = i*Kf*m
with i = 1 for ethanol

For HCL,
delta T = i*Kf*m
with i = 2 for HCl.
and