You may have noticed that latex helium balloons tend to shrink rather quickly; a balloon filled with air lasts a lot longer. Bal- loons shrink because gas diffuses out of them. The rate of diffusion is faster for smaller particles and for particles of higher speed. Diffusion is also faster when there is a large difference in concentration between two sides of a membrane. Given these facts, explain why an air-filled balloon lasts longer than a helium balloon.