What is the difference between the states of matter and the phases of matter? Should solid, liquid and gases be called states of matter or phases? How many states and phases are there? Different sources quote different things. Please help

up vote 3 down vote accepted

States are more the gas/liquid/solid thing, describing the qualitative behavior of some matter.

Phases describe a collection of matter (often a region) as opposed to that collection's state. This can be confusing because we often refer to phases by their state for convenience.

For example, multiphasic liquid systems have several phases but only 1 state (liquid). A common example is oil and water when the two don't mix; then, there's an "oil phase" and an "aqueous phase".

This might be confusing since some simple examples have one phase per state. For example, when we talk about water boiling, there's a "liquid phase" and "gas phase". Here the regions are the phases and the gas/liquid qualifiers describe the state of matter in them.

  • What is plasma? What are Bose-Einstein condensates? Are they states or phases? sometimes paramagmet to feromagnetic phases are talked about. – mithusengupta123 Apr 27 at 21:08
  • @mithusengupta123 If you're referring to the nature of the matter, e.g. you're describing that the matter is behaving like a plasma, then you're referring to its state. But if you're referring to the collection of matter itself, then you're referring to a phase. For example, if you have a plasma, then you have a plasma phase that contains matter in the plasma state. – Nat Apr 27 at 21:25

it is the same thing. but we say phase transition. and states of matter. phase transition is when the state changes.

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