## Pure Liquids and Pure Solids

Nathan Mariano 2G
Posts: 51
Joined: Thu Sep 27, 2018 11:29 pm

### Pure Liquids and Pure Solids

Pure liquids and pure solids are able to react in chemical reactions. Therefore, I do not completely understand the reason why pure liquids and pure solids are not contained in the equilibrium constant. Can someone explain this to me?

kateminden
Posts: 48
Joined: Thu Sep 27, 2018 11:24 pm

### Re: Pure Liquids and Pure Solids

Pure liquids and pure solids are not included in equilibrium constant expression because their densities (and, therefore, concentrations) are constant, so they do not affect the reactant/product amount at equilibrium.

Anusha 1H
Posts: 53
Joined: Thu Sep 27, 2018 11:15 pm

### Re: Pure Liquids and Pure Solids

Because the molar concentrations of solids and liquids don't change during a reaction, they are not included in calculating the K value

Chem_Mod
Posts: 16489
Joined: Thu Aug 04, 2011 12:53 pm
Has upvoted: 349 times

### Re: Pure Liquids and Pure Solids

The activities of pure liquids and solids are technically included in the equilibrium constant, but their activities do not change during the reaction, so the value of 1 is accurately used for their activities (or concentrations).

Nina Do 4L
Posts: 49
Joined: Thu Sep 27, 2018 11:27 pm

### Re: Pure Liquids and Pure Solids

Pure solids or liquids aren't included in the equilibrium expression because their concentrations stay constant throughout the reaction so we don't include them.

Rian Montagh 2K
Posts: 48
Joined: Thu Sep 27, 2018 11:15 pm

### Re: Pure Liquids and Pure Solids

I'm still confused about this concept. For example, with the reaction CaCO3(s) <--> CaO(s) + CO2(g), how do the molar concentrations of the solids not change?