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.
Diffusion is a spontaneous movement of particles from an area of high concentration to an area of low concentration. Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a more concentrated solution, up a concentration gradient.