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.
Naturally, molecules move from an area of high concentration to low concentration without the need of energy. This type of movement is passive transport. Molecules with strong electrical charges such as ions cannot simply diffuse across the cell membrane. Irrespective of their size, their charge prevents them from moving freely across the cell membrane.