Bromine gas diffusion. Bromine vapour (orange) filling a gas jar as it evaporates from bromine liquid (dark brown, bottom of jar). Because gas molecul

Bromine gas diffusion. Bromine vapour (orange) filling a gas jar as it evaporates from bromine liquid (dark brown, bottom of jar). Because gas molecules can move independently of each other and do so randomly, a gas spreads out from its source in a process called diffusion. The diffusion rate depends mainly on the temperature and the medium through which the diffusion takes place. In this case, the medium is air. The gas colour allows the upwards diffusion from the liquid to be observed.