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.
In diffusion, solute molecules move from an area of high concentration to low. No barrier ( like a cell membrane) is required. In osmosis, water molecules move from an area where they are relatively concentrated (I.e. a dilute solution) to a solution that is more concentrated (where there are more solute molecules and fewer water molecules).