ICE tables

[605720459 1I]

When creating an ICE table to find H30 concentration or OH concentration for weak acids and bases, should H20 be included in the reactants side? In the example during Wednesday's lecture, H20 was not included, and I am unsure why.

[Allison Peng 1D]

Liquid water is usually not included in equilibrium calculations since its concentration virtually does not change between the reactant and product side (assuming water is greatly in excess)

[Sasha Gladkikh 2A]

For ICE tables, only aqueous solutions and gases are included.

Therefore, H₂O_(l) is not included in the ICE table, rather it is simply crossed out. This applies to all liquids and solids.
Conceptually, H₂O_(l) is not included in the ICE table because it is in such large excess that its concentration change is essentially immeasurable/negligible.
Note: In Chem 14B, we always assume that we are working with dilute solutions, in which our solvent (i.e., water) is in large excess.

[Joseph Lee]

No you omit H20 in the ICE tables because it is almost always in excess and so it will not contribute to the reaction's concentrations

[SerenaSabedra]

ICE tables do not include liquids or solids, and because we assume H2O is always our solvent and is therefore a liquid, we don't include. This is because H2O concentration remains unchanged after a reaction because there is a much larger quantity of it in the system.

[Kimia Rategh 2A]

Hi! When creating an ICE box for a reaction, you would not include H20. This is also the case in with equilibrium constants, we would not include the concentration of h20 to find K. This is because liquids like H20 are usually present in a reaction in excess and therefore their concentration throughout the reaction does not really change. Furthermore, because they are present in excess and therefore present on both the reactant and product side with similar concentrations, putting it in the equilibrium constant would just make it so that the values cancel out. This same logic can be applied to including H20 in ICE boxes. Since the goal of ICE box is to find the equilibrium concentrations of a reaction with a weak acid or base involved, there is no need to find the concentration of H20 and therefore you do not need to include it.

Hope this helps!

[emmakvarnell]

H2O isn't included because the only molecules that should be included must be in an aqueous or gaseous state. H2O is a liquid.

[Charlotte McDonough 2B]

Hi! H2O is a liquid and is in such high concentration as the solvent that a slight change in concentration will not have a notable change in final concentration compared to initial concentration.

[Divya Mehta 2K]

Liquids and solids don't change concentrations enough/much enough to note, so the ice tables only include gases and aqueous solutions