161
Chemistry / Re: How cold can ice get ?
« on: 31/03/2006 17:47:05 »
You certainly have a lot of states here. However, most of these are not true "states" if we're talking about pure materials. As soon as you add a second (or more) component to a system, properties can change dramatically.
Gas
Ideal gases only are theoretical entities, but in any case are just examples of gases. Many gases have properties very similar to ideal gases, but ideal gases don't exist in reality.
"Real gas" refers to any gas that exists.
A "supercritical fluid" is a type of gas that exists above its critical temperature and critical pressure. As long as you are above the critical temperature of a gas, that gas can not be condensed into a liquid. Exact definitions vary a bit, but this is my favorite).
"Critical opalescence" is a _property_ of supercritical fluids very near the critical temperature and pressure. Many properties are very odd in this region.
Liquids
A superfluid is a liquid that has no viscosity, but still a liquid. Superfluids will actually flow uphill.
Mixtures
Colloids, suspensions, etc. are mixtures, so are not generally considered separate "states".
Solids
Viscoelastic materials are generally considered to be solid. Note that even normal metals can flow given the right stresses. Also, glass used to be considered viscoelastic and was thought to be a supercooled liquid. This is now known to be false.
Refractory, crystalline, glass, etc. are simply different types of solid, not true "states" in the chemical sense.
DrDick
Gas
Ideal gases only are theoretical entities, but in any case are just examples of gases. Many gases have properties very similar to ideal gases, but ideal gases don't exist in reality.
"Real gas" refers to any gas that exists.
A "supercritical fluid" is a type of gas that exists above its critical temperature and critical pressure. As long as you are above the critical temperature of a gas, that gas can not be condensed into a liquid. Exact definitions vary a bit, but this is my favorite).
"Critical opalescence" is a _property_ of supercritical fluids very near the critical temperature and pressure. Many properties are very odd in this region.
Liquids
A superfluid is a liquid that has no viscosity, but still a liquid. Superfluids will actually flow uphill.
Mixtures
Colloids, suspensions, etc. are mixtures, so are not generally considered separate "states".
Solids
Viscoelastic materials are generally considered to be solid. Note that even normal metals can flow given the right stresses. Also, glass used to be considered viscoelastic and was thought to be a supercooled liquid. This is now known to be false.
Refractory, crystalline, glass, etc. are simply different types of solid, not true "states" in the chemical sense.
DrDick