definition of effusion in chemistry
A when a volume of gas is opened to another volume with less pressure, the gas can either diffuse or effuse into the container. The main difference between diffusion and effusion is the barrier between the two volumes. Answer: Effusion is when there is a barrier with one or many small holes that prevent the gas to expand into the new volume unless a gas molecule happens to travel through the hole. The term small when referring to the holes are holes with diameters less than the mean free path of the gas molecules.