Effusion and diffusion
Effusion
In the 19th century, Thomas Graham found that the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles. Graham's law of effusion is as follows: Rate of effusion for gas 1 / Rate of effusion for gas 2 = sq rt. M2 / sq rt. M1, where M1 and M2 represent the atomic or molecular weights of the gases as appropiate.
In its simplest form, diffusion is the transport of a material or chemical by molecular motion. If molecules of a chemical are present in an apparently motionless fluid, they will exhibit microscopic erratic motions due to being randomly struck by other molecules in the fluid. Individual particles or molecules will follow paths sometimes known as "random walks."
In such processes, a chemical initially concentrated in one area will disperse. That is, there will be a net transport of that chemical from regions of high concentration to regions of low concentration.
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Acid Rain
