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Date: 1999 


Question:
Are there any substance that can exist in all three of the states of matter at the same time? If so what is its classification name? damian



Replies:
Water...put a piece of ice in a hot frying pan. You'll see a solid liquid and gas of the same substance right before your eyes. That's one off the top of my head...I'll see about any more. I don't Know what you mean by classification, though. E-mail me with more info if you like. Solid carbon dioxide (dry ice) almost qualifies, but it never gets to the liquid phase since it sublimes (s--->g).

-Joe Schultz


For most substances, there is a particular temperature and pressure at which all three states (gas, solid, liquid) exist in equilibrium. This is called the triple point on a phase diagram. (A phase diagram of a substance simply gives the stable phase of a substance as a function of the temperature and pressure.) The triple point of water occurs at 0.01 degrees C and 0.006 atm. Also, please remember that you CANNOT see water as a gas... When you see "steam" you are really seeing small droplets of water in the liquid phase. Water in the gas phase is colorless. -Certainly, if I drink a glass of ice water (with ice cubes in the water on my deck here in "humid Florida" - all three states of water are present (not in equilibrium) - but I only see the two states (solid and liquid).

Dr. Brown



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