Chem Question reg Equilibrium

[masochist]

[theloserwins]

Weird. I used to be taught that H2O should be included in equilibrium calculations.

[Sonneteer_Trombonist]

You can only use gases and aqueous solutions as part of the equilibrium constant equation. The brackets in the equation represent concentrations, and a solid object or a liquid has no concentration.

Edit: Just found this video, this guy is pretty good.

Edited August 21, 2010 by Sonneteer_Trombonist

[x___x]

When water is in gas form it should NOT be omitted.

Regarding the things that should be omitted and the things that should not, I'm quoting this explanation from "Chemistry" book by John Green and Sadru Damji:

"The concentrations of certain substances remain constant, so these are omitted from the equilibrium constant expression. All solids have a fixed density and hence a constant concentration, so these are omitted. For example in the equilibrium:

NH₄Cl _(g) <--> NH_3(g)+ HCl _(g)

The equilibrium constant is simply given by

K_c = [NH₃][HCl] mol² dm^-6

because the costant concentration of the solid ammonium chloride is omitted. The concentration of any pure liquid is also constant as it too has a fixed density. This is particularly important for the concentration of water which is taken as constant and omitted for equilibria in dilute aqueous solutions."

Edited August 21, 2010 by x___x