Why is it that if I leave temp high, water alone boils without spilling out of the pot, but if I add something to it (like pasta, chai mix, etc) and leave it on high, it eventually boils over and spills everywhere?
In: Chemistry
Water doesn’t boil over. Steam creates bubbles but the bubbles quickly collapse.
However, add stuff that changes the physical properties of the water and the bubbles can persist and stack on each other until the water “boils over” the pot.
There are various ways to favour bubble formation.
At the macro level, lower surface tension or higher viscosity both work (soap vastly decreases surface tension, pasta starch increases viscosity without much changing tension).
At the micro level you might want to Google “micellar aggregation” which demonstrates how amphiphilic molecules like soap help support structures like bubbles in water. In brief: amphiphilic molecules are long rods with one end attracted to water and the other repelled, they can line up on the surface of water with their hydrophobic arse in the air. A thin bubble surface can have these molecules on both sides of the surface and collapsing the bubble forces the hydrophobic ends back into the water which is energetically unfavourable.
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