How much would the freezing point of water decrease if 4 mol of nacl were added to 1 kg of water (kf = 1.86°c/(mol/kg) for water and i = 2 for nacl)?

ΔT(freezing point)  = (Kf)m
ΔT(freezing point)  = 1.86 °C kg / mol (4 mol / kg)
ΔT(freezing point)  = 7.44 °C
Tf - T = 7.44 °C
T = -7.44 °C

the molecules move in straight line until they collide with each other or with the walls of the container. collisions are perfectly elastic; when two molecules collide, they change their directions and kinetic energies, but the total kinetic energy is conserved.

explanation: