Why a Chest Tube is Placed. A chest tube is placed for a variety of reasons. One reason, as you mentioned, is to help the lung re-inflate when someone has a collapsed lung, also known as a pneumothorax. In that circumstance, a chest tube is inserted along the side of the ribs to allow the lung to reinflate.
A. Osmosis is the passive movement of water from an area high in water concentration, across a semi-permeable membrane, to an area low in water concentration.
Facilitated Diffusion Osmosis - the diffusion of water (across a membrane) Water will move in the direction where there is a high concentration of solute (and hence a lower concentration of water. A simple rule to remember is: Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction.