Ask A Scientist Chemistry Archive

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

Answer 1:  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
 
Answer 2:  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-Dr. Brown