Equilibrium Phases?

[305597516]

Hello, I noticed in the first lecture that Professor Lavelle mentions that when reactants and products are in the same phase, this is referred to as "homogenous equilibrium," and when they're in different phases, it's is called "heterogenous equilibrium." What exactly did he mean by phases?

Does R and P being the same phase mean they're in equilibrium at that moment and a different phase mean they're in the process of reaching equilibrium? Or are phases something completely different that we'll learn about later?

[Sohan Talluri 1L]

I believe Professor Lavelle was referring to whether the reactants/products were in the solid, liquid, or gaseous phases. Certain phases like solids and pure liquids are not included in equilibrium calculations, and if a reaction is in heterogenous equilibrium, conversion between partial pressures for gases and concentrations for liquids might be necessary in order to find the equilibrium constant.

Hopefully this helps and please correct me if there are any mistakes.

[Vy Le 1G]

Hello,

Like mentioned previously, when we say “phases” we really mean the state of the molecules— liquids, solids, gases, aqueous, and such. For instance, if a chemical reaction consists of all gases, it is a homogeneous equilibrium of gases and we can calculate Kp. As for heterogenous mixtures, keep in mind we don’t include solids or liquids in our calculations.

Hopefully this helps!

[Brynn 2F]

I believe he emphasizes this also in order for us to keep in mind which state each molecule is so we know what to include in our equilibrium constant equation (solids and liquids should be left out and are usually in heterogenous equations).

[Skylar Lo 2C]

It would represent different states of matter I think

[ashna kumar 3k]

It is important to distinguish between the heterogenous phase and homogeneous phase as it impacts what is included in the equilibrium constant. Remember, we only include gas phase and compounds denoted aqueous in our equilibrium constant. If the whole reaction is homogeneous in the gas phase, then we don't have to worry about what is included in K, as it is all components. However, in a heterogeneous reaction, we need to make sure to omit solid and liquid phase compounds from K. Liquids are not included because often times it is the solvent and is present in excess, so the amount of it doesn't change on the products and reactants side. For solids, it doesn't make sense to talk of it in terms of concentration, which is why it is not included.

[amara ajon 1d]

Hi,
"Homogenous" simply refers to how all of the compounds in equilibrium are in the same phase (gaseous or aqueous) whereas "heterogenous" means that we have compounds in two different phases in the same chemical equilibrium reaction.

[Irene Kim 3E]

The terms 'homogenous equilibrium' and 'heterogenous equilibrium' refer to the states of matter of the reactants and products involved in an equilibrium expression. Also, I believe we learned that when calculating equilibrium values, we tend not to include solids and liquids. Moreover, when all of the products and reactants are gases, we can write equilibrium as K_p in terms of pressure instead of K_c in terms of concentrations.

[Sophia Manos 1F]

Hi! By phases I believe he meant states of matter, and so when referring to them as homogenous he means that they are all currently the same state. It is important to make note of what phases there are because in equilibrium calculations we only include substances in gaseous and aqueous states (we do not include pure liquids or solids). Hope this helps!