Ask A Scientist Chemistry Archive

Question:
I notice that when I leave a glass of water out all night that
the next morning it developed little bubbles in the water.  Why
do these bubbles appear?
 beth a berry

Answer:
I would imagine this:  There are gases (like carbon dioxide, oxygen, etc)
dissolved in water.  When water is heated, these gases are less soluble
in the water.  When you boil water, the bubbling is dissolved gases being
released.  So I would say that leaving a glass of water out all night
lets the water "warm" up and those bubbles are bubbles of oxygen, carbon
dioxide, etc being released.  No, you're not boiling the water by leaving
it out...the gases are just less soluble at the warmer temperature.
-Joe Schultz