Difference Between Diffusion and Osmosis


I doubt that you will ever see Bill Nye lounging in a steam filled bathroom surrounded by lavender scented bubbles, candle light, soft piano music playing on Pandora and a glass of wine. Then again, I do not profess to know what Mr. Nye does in his spare time. I however, enjoy the occasional glass of Riesling, a good book and a relaxing stint in a hot bath. Hot water, a sweet adult beverage and peace and quiet works wonders to relax the muscles. “But how does one learn anything about science in this condition?” you ask. A very good, observatory question indeed and one I can answer, though in my own special way.

I have never claimed to be a scientific type of gal, no not me. In fact, I couldn’t tell you the difference between a polymer and a hadron or if they ever cross paths, so when I was asked to write an article explaining the difference between diffusion and osmosis, I admittedly panicked and grabbed a glass, a cork screw and a bottle of wine. How does a girl, like me, explain that? Another good question, you are amazing. Clearly you have an interest in science, or a good bottle of wine

I could go on and on about solvents, solutes and semi permeable membranes…okay, I really couldn’t, who are we kidding but, I can give you some good examples to help you understand the differences between diffusion and osmosis in a more “everyday living” type of way. With the help of my relaxation methods, my steamy bath and my trusty side kick, Sir Glass o’ Wine I shall take you on a journey, a journey of daily science in the life of an everyday girl. (Cue theme music here.)

Let us begin with diffusion, now our buddy Bill would tell us that diffusion is the process of a solute and solvent moving together to achieve and equal distribution, or meld. If you are anything like me, here is where you take another big gulp of wine and look straight ahead, wide eyed, as you nod your head, faking understanding. It is actually very simple. Diffusion is the process of spreading something evenly throughout another something, be it liquid or air. Take for example the scented candles I have lit to create an ambiance within the respite of my bathroom. The candle emits a perfume that begins to permeate the air. At first it is only detected close to the candle but, as it burns the vanilla scent spreads into the room eventually, mingling together with the air to fill the entire room with its wonderful aroma. It blends with the room air evenly dispersing itself. Not quite there? Okay take another sip.

Think about your glass of wine, did you add ice? If so, then that ice is slowly melting and mixing into your wine, although unpleasant as an example, the water from the melted ice is diffusing into your wine, meaning it is mixing equally though the contents of your glass. The water and the wine blend together, filling the space of your glass in an equal blend. By the way, that alcohol you have just ingested is now moving into your blood stream by virtue of diffusion. It is combining with your blood to make a blended disbursement of blood, oxygen and wine, making us both equally intoxicated. Let’s move on.

Osmosis is also the act of having two products “mix” but, it involves water or a product of water and a barrier that has the ability to absorb the liquid and redistribute it, all be it not always as an equal blend. I know, I know, that may have been a bit more “Nye” than everyday science gal. Let’s take this ordinary bath pouf sponge for example. Feel its composition, its dry, rough and unyielding. If we drop it into the bath water, what happens? I’ll give you a minute. See what it does? It absorbs the bath water into its nooks and crannies. The pouf is no longer dry and harsh it has now expanded and become pliable, more user friendly. That is due to osmosis; the water has passed through the surface of the dry sponge and dispersed itself into the empty spaces to create a water laden luffa. Wait, you still have that wide eyed, doe look. Is that the wine or the science?

What if we get into the water? What happens to our skin? If we soak here long enough and drink all our wine, not only will we be fully relaxed and tipsy, but our skin will look like the wrinkled, shriveled surface of a prune. When you were a kid did you ever wonder why this happened? Osmosis, that’s why! Our skin acts as a semi permeable barrier for the bath water. The warm water passes through our pores, the empty space, and in turn hydrates our head and shoulders, knees and toes, knees and toes. Oh wait, that’s the wine talking. The water has “mixed” with our skin molecules and through osmosis “blended” into the available space. I can tell by the look on your face you get it. My work here is done.

So ends my spiel on the difference between diffusion and osmosis from and everyday girl’s perspective. I hope that it helped you to understand the science of it in an “everyday” kind of way. If not, then at least we had this moment with good wine, good friends and a nice bath. Cheers!