Water will diffuse back and forth across the membrane but the NaCl and sucrose will stay where they are. All three molecules will diffuse back and forth until the concentrations of each is the same on either side of the dialysis membrane. Only the NaCl and sucrose will diffuse. Only the water and the NaCl will diffuse. Only water and sucrose will diffuse until they reach equilibrium.
Water diffuses from where the water is more concentrated to where the water is less concentrated.
Water diffuses from where the dissolved solutes are more concentrated to where the dissolved solutes are less concentrated. Water diffuses from hypertonic to hypotonic. Water diffuses into cells. Water diffuses into sea water. Shown to the right is a model system.