H2O in K Expressions

[Sarah Zhari 1D]

Water as a liquid is not included in K expressions, but would we still include H2O gas in K expressions?

[Jessica Katzman 4F]

Yes, H2O gas is included in K expressions.

[Vicki Liu 2L]

H2O as a gas should be included because changes to its partial pressure are notable. As a liquid, however, H2O is present in excess and there is essentially no change in its concentration before and after reaching equilibrium.

[BCaballero_4F]

Since it is H2O as a gas, you would still include it.

[Nathan Nakaguchi 1G]

Only liquids and solids are supposed to be ignored in K expressions. While it is H2O we're talking about (which tends to be liquid and therefore ignored), if it is in the gas phase it should be used in the expression.

[Amir Bayat]

Yes, pure substances are the only forms of a substance which are not included in the equilibrium constant. Gases and aqueous solutions are not pure substances.

[Jasmine Vallarta 2L]

solids and liquids aren't included. Only (g) and (aq)