When the osmometer was set up, the solution in the beaker was hypotonic relative to the solution in the dialysis bag, hence, the net movement of water is into the bag. ... As the water moves into the bag, pressure is generated forcing water up the column.

What cause the fluid in the osmometer to rise?

When water molecules enter the open osmometer, they do add volume to the solution, causing the solution level in the osmometer to rise (graphic). As the solution level rises, its weight applies hydrostatic pressure to the membrane and to the water molecules near the membrane.

Why does water move from low to high solute concentration?

Osmosis is a passive transport process during which water moves from areas where solutes are less concentrated to areas where they are more concentrated. The water level on the left is now lower than the water level on the right, and the solute concentrations in the two compartments are more equal. ...