Why isn't my "home brew" hand sanitizer working "properly?"

But, again, if you dilute a non-neutral pH solution, aren’t you bringing the solution closer to 7?

I’m assuming here that “alcohol” here means a mixture of alcohol and water, since that’s what alcohol always is without pretty crazy chemistry involved.

Isn’t all this discussion beside the point that glycerin, ethanol, and water are all mostly polar, shouldn’t they be mutually miscible?

What is supposedly the non-polar layer in OP’s concoction?

So in my earlier post, I was focusing on the addition of an alcohol, and ignoring the dilution factor. That was an oversight on my part. Let me modify my answer accordingly:

In general, yes, but not as much as you might think. Most natural waters, beverages, and consumer products (like shampoos and skin lotions) are buffer solutions that resist changes in pH.

And because the pH scale is logarithmic, even simple dilution doesn’t change the pH as much as you might think, especially when you are discussing weak acids and bases (which don’t completely disassociate).

For example, the pH of a 0.1 M solution of acetic acid (the acid in vinegar) is about 2.87. If I dilute it by 100% to get a solution of 0.05 M acetic acid, the resulting pH is about 3.03 (which is indeed closer to neutral).

However, suppose you have a buffer solution composed of 0.1 M acetic acid in solution with 0.1 M sodium acetate. The pH of this solution is about 4.7449.

If I dilute this buffer solution by 100% to get a solution of 0.05 M acetic acid in solution with 0.05 M sodium acetate, the resulting pH is 4.7450. In other words, virtually no change at all.
Finally, note that most water isn’t actually pure. Even distilled and/or deionized water that is exposed to air, for example, has dissolved CO[sub]2[/sub] in it (which in water is equivalent to carbonic acid), which when hydrated produces hydronium ion and bicarbonate ion. At equilibrium, the pH of water exposed to air is about 5.7.

One would think so. However, note that the reason that polar substances dissolve in water is because they form hydrogen bonds between the solute molecules and water molecules.

With that said, not all polar molecules necessarily form the requisite hydrogen bonds with water. This paper discusses some of the exceptions.

However, none of the substances under discussion fall into any of these exceptions. Glycerin (aka glycerine and glycerol) is a type of alcohol, as is ethanol, of course.

Good question. Maybe there’s something else in there.

Thanks for the mini Chemistry lesson :slight_smile:

Can’t you just use soap?

I made hand sanitizer, because I couldn’t find any to buy, and I wanted it to carry, for occasions when hand-washing was not available. I already had a hand lotion that was pretty much all aloe and cocoa butter. I had isopropyl alcohol. Mixed them together, and they didn’t mix well. Had to agitate them to an extreme degree-- that is, really, really shake the bottle, long and hard (yes, I heard it). But they did eventually mix. And they stayed mixed. I made a liquid measure of the stuff, and put it into some little bottles that were 6 for 99 cents (I used 4 of them, so they held 1/4 c., or 4 tbsp., each).

I don’t know how well the stuff is working, but it’s stronger than a recipe I found online, and I checked a couple of recipes. They all were about 1:1 99% alcohol to aloe. I had only 70% alcohol, so mine is 3:1. The consistency is perfect, though, probably because of the cocoa butter. I had some peppermint essential oil, and I added just a few drops, so it smells like my peppermint soap, instead of alcohol, and I read that peppermint is a very mild germicide. Don’t know if that’s true, but a few drops (literally, maybe three), shouldn’t alter the mix much.

It certainly is making my hands soft, which is good, because all the handwashing is cracking my skin a little.

Yes, I wash any time there is the opportunity, but when I’m out, say, walking my dog, and I have to pick up her poop, I want to sanitize my hands after. Washing would be better, but in the middle of our walk, isn’t possible.

I mixed Everclear 2/1 with moisturizer. Kinda runny, didn’t mix well. I assume it works though.