Question

what do you understand by the term Kf for water is 1.86K Kg mol-1?

Answer 1

Kf is the molal freezing point depression constant of the water is 1.86 °C/m when moles of solute per kilogram of water is unity.

∆Tf = i kfm

When , i (Van't Hoff Factor) = the number of dissolved particles in water is unity then

∆Tf = kfm

For this the value, Kf is 1.86 °C/m.