Relative rates of effusion through punctured balloons

Abstract

Numerous methods of demonstrating relative rates of gas diffusion have been successfully employed. From the diffusion of ammonia and hydrogen chloride through a narrow tube, to the passage of gases through a porous cup, these methods provide a vivid illustration of Graham's Law in both qualitative and quantitative fashions. Graham's Law also applies to gas effusion rates, which can be demonstrated by the passage of gases through a hypodermic needle into an evacuated flask. All of these demonstrations require either corrosive chemicals or access to a modest amount of glassware and equipment. A simple method of demonstrating relative rates of gaseous effusion which requires no corrosive chemicals or glassware is reported here.