Maximum Yield USA 2016 June | Page 70

PURIFYING YOUR WATER When thinking of osmosis, reverse or otherwise, one might be reminded of a bit of circular reasoning seen on a geeky T-Shirt: “In order to understand recursion, one must first understand recursion.” It’s a math joke. Osmosis is kind of like that because in order to understand reverse osmosis, one must first understand osmosis. Please review the definitions in the terminology sidebar found on page 80 before proceeding with this article. Osmosis Basics Osmosis is a fundamental chemical and biological concept taught in both middle and high school, but some people find the concept hard to grasp. Osmosis is a kind of diffusion. When we think of things diffusing, we don’t have much trouble with the notion that, if given the chance, the atoms or molecules of gases and solutes in a liquid solvent or in the air tend to naturally spread out and randomize rather than come together. “ 68 Maximum Yield USA  | June 2016 For osmosis to occur, a barrier must exist between two solutions that have different solute concentrations.