‘Foam-tastic’ – Temperature and Surface Tension

Equipment:

Space, Beaker or empty 2L drink bottle, iodine + peroxide + dishwashing liquid OR water + dishwashing liquid + liquid nitrogen

Instructions:

Combine all ingredients EXCEPT the Peroxide or the Liquid Nitrogen. Clear a space and then add the final ingredient.

Science:

The iodine causes the peroxide to undergo an exothermic reaction that produces a large number of very small bubbles. The reduction in surface tension caused by the addition of dishwashing liquid, a surfactant, prevents the bubbles from bursting like they usually would in water leading them to billow ‘up and out’.

For liquid nitrogen and water, the temperature of the liquid nitrogen, ~200 degrees below zero,  causes the Nitrogen to boil and produce bubbles. Just like above the dishwashing liquid reduces the surface tension and prevents popping so you get lots of foam!