[tomd]

I'm hoping someone out there might have some ideas.

I would like to give a demonstration to the kids in my wife's villiage in rural Thailand next month. Last time I was there, I promised I would show them how to make an alcohol gel. I've never actually done this mind you, but I've read about it. They use these small alcohol chafing gels all the time in Thailand at the restaurants. This is similar to Sterno in the U.S. I thought this was a very practical application which could be made with materials around the farm. It might not only help them to take an interest in chemistry but could save them a few baht as well.

However, I can't seem to make it work. The experiment is supposed to simply involve making calcium acetate using vinegar and lime. This part seems to go OK. I get a lot of gas when stirring the lime in vinegar and after evaporation I am left with a white powder which I can only believe is calcium acetate.  I've tried several different brands of vinegar, and used both agricultural lime as well as crushed egg shells in making this powder. It always seems to work.

Since I live in Bangkok and don't have access to a still, I went to the store and purchased a can of 99% methanol. In the villiage they'll distill their own ethanol. Unfortunately, whenever I pour the methanol into my solution of aqueous calcium acetate I never get a gel. In fact, nothing happens at all. I've also tried 70% isopropal alcohol, worried that maybe my methanol wasn't really what the can said. That didn't work either. In frustration I took a medical syringe and added methanol 1 cc at a time to the most concentrated solution of calcium acetate I could make. I started from a ratio of 10:1 acetate to alcohol, and worked up to 1:10 acetate to alcohol. No combination resulted in a gel.

I feel bad because I promised the children I would show them this, and in my own inquisitive mind I'd like to understand what is happening also.

Is there something that I am missing? The sites on the internet imply this is simple, but it doesn't seem to be working for me. Is there a specific temperature or conditions under which this works? Could there be some impurities in the water which I am using which might be affecting the solution? I have been using bottled water for the experiments.

Can anyone think of simple tests I could run with equipment around the house that might give me an idea of what I have and why the gel isn't gelling?

Thanks for any ideas,

Tom

[Borek]

Never heard about whole procedure - can you post some links to the sites where it is described?

Are you roasting your calcium acetate to make it dry?

Why do you use methanol and isporopanol instead of ethanol?

Edit:

OK, did some digging and Googling. The only thing which you don't state is the concentration of calcium acetate you used - perhaps your solution concentration (before you add alcohol) is too low/high? Have you tried to go through the solid acetate, just to be sure you control its concentration?

http://zenstoves.net/Sterno.htm states you should use

1 part dry calcium acetate (by volume) to 2 parts water

No idea what kinds of vinegar you can buy in Thailand - are they strongly flavoured? If so, your solution may contain large amounts of inert salt (like NaCl) and I wonder if it will not prevent gelling.