Re: we did a bubble project using glycerin - What does it do to bubbles?

Ive found an absolutely wonderul site on the internet that will answer just about all your bubble questions, it certainly has lots of infor on why bubbles have the shape they do. Its all about interactive forces between the detergent or soap and the water, complex chemical interactions forming rather simple things...like bubbles. the site is

SOAP AND BUBBLE INFO HERE

Now as for gylcerin, this ones a little more difficult, I couldnt find any foolproof answer but as far I can see it could have one of two properties that wil aid bubble formation.
1. It's thick and strong. It will toughen up the weak detergent you are using to make the bubbles. Gylcerin mixes well with both detergent and water so it would strengthen the bi-layer structure (see the link above for details of bilayers) of the bubble walls, therefore making them last longer.

2. Glycerin is hydroscopic, thats just a big word for meaning it sucks in water, and one of the main reasons bubbles pop is the water that forms them evaporates. So if glyercin would suck water out of the air and add it to the bubble wall, it would replace the water that is naturally evaporating from the bubble. The total effect of this would be to make the bubble last longer.

If you want some more info on bubbles theres another great answer found here on Madsci.org and you can find it using the link I've added below.

SOAP AND BUBBLE INFO

Hope that helps answer your question.

David Barker