# What is the difference between a chemical state and just a combination?

I don't think a combination also can be called a "state" i.e. that the chemical state of vapour or solid would be just a combination. When I read Wikipedia about "chemical state" it refers to just a combination. But AFAIK, an entity that has just combination does not have a state. So how do we know what is a state and what is just a combination?

You seem to be confused with "state of matter"/"phase" and "chemical state".

The chemical state encompasses all the macroscopic parameters necessary to fully define a given system. For example, "pure $\ce{O2}$ at $1\:\mathrm{atm}$ and $100^{\mathrm o}\:\mathrm{C}$" is an example of chemical state. A more complicated example would be something like: "10 moles of liquid $\ce{O2}$ at $-100^{\mathrm o}\:\mathrm{C}$, mixed with 1 mole of gaseous $\ce{O2}$ at $1\:\mathrm{atm}$ and $100^{\mathrm o}\:\mathrm{C}$ and 2 moles of gaseous $\ce{N2}$ at $1\:\mathrm{atm}$ and $200^{\mathrm o}\:\mathrm{C}$" (Yes, this isn't at equilibrium)

On the other hand, the phase or sate of matter only applies to a homogeneous system. A gas is in gas phase, but a system consisting of a gas and a solid doesn't have a phase/state of matter. Note that if a gas/solid is dissolved in liquid, then the phase is liquid since solutions are homogeneous.

• Thank you. It looks like a chemical state refers to a combination and also properties around it. – Niklas Mar 9 '13 at 16:42