– Why does putting the top on a pot of boiling pasta make it frothy and boil over?

Question

– Why does putting the top on a pot of boiling pasta make it frothy and boil over?

In: Chemistry

Answer 1

The lid traps heat and steam ~~, building a little pressure, which can lower the boiling point~~ . It may not be a lot, but can be enough.

This then causes the pot to boil more, as it would if just cooked over a higher temperature.

The frothy bubbles come from the starches in the water, giving a little extra strength to the surface tension. This doesn’t have anything to do with the lid, though.

Edit: pressure increases increase boiling point, but pressure on stove top pot not likely to amount to much