Vapour in Air Diffusion Apparatus

Using a small sample of the liquid in a narrow vertical tube, and observing its rate of evaporation into stream ofair passed across the top of the tube can conveniently be used to study the diffusion of vapour of a volatile liquid into air. The set up consists of a glass tube placed in awater bath. A horizontal glass tube is fixed to the upper end of the tube and air is drawn through this by a smallair pump included within the unit. Air flows over this tube maintaining partial pressure difference. A traveling microscope with sliding vernier scale is provided to measure the rate of fall of solvent within capillary. A stirrer is fitted to maintain constant temperature inside the bath.