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What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Thu Jan 09, 2020 6:43 pm
by Andrew F 2L
Why does it matter if a chemical reaction is a homogeneous or heterogeneous equilibrium? Is it only to differentiate what to include or not include when finding the equilibrium constant?

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Thu Jan 09, 2020 6:56 pm
by Uisa_Manumaleuna_3E
From what I understand, yeah, pretty much we learn homogeneous and heterogeneous to know what to include in the K or Q calculations. Because, really, we already recognize the phases of the molecules anyway, it just helps specifying where we include all the concentrations/partial pressures (as we do in homogeneous) and when we don't (in heterogeneous).

Re: What is the Importance of homogeneous vs heterogeneous equilibria  [ENDORSED]

Posted: Thu Jan 09, 2020 7:34 pm
by Ryan Yee 1J
Yes, from what I gathered in the lecture, its only purpose is to specify the states of the reactants and products in an equilibrium equation and what to include in a K or Q calculation for an equation.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Thu Jan 09, 2020 7:41 pm
by DanielTalebzadehShoushtari2A
It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 12:19 am
by Amy Xiao 1I
DanielTalebzadehShoushtari2A wrote:It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species.


Thank you for pointing that out! We would have to convert everything into concentrations, not partial pressure, if there are aqueous solutions present.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 1:42 am
by RobertXu_2J
I believe the importance of homogeneous and heterogeneous equilibria is that for homogeneous equilibria, you do not have to worry about which of the materials are needed for the equilibria equation, whereas for heterogeneous you have to realize that solids and liquids are excluded.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 8:40 am
by Justin Quan 4I
To add on, for a homogeneous gas mixture, we can simply include all the gas species when calculating K or Q. However, if there is a heterogeneous equilibria, chances are there is a solid or liquid species. Hence, you will have to be careful to exclude all liquid and solid species when calculating K or Q.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 9:14 am
by Ruth Glauber 1C
I think that it's only purpose is to narrow in on the states of the reactants and products in the equilibrium equation, so you know what to include in a K or Q calculation for an equation.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 11:15 am
by gabbymaraziti
I believe it is important so that we use the correct state when calculated K (using brackets for aqueous reactants/products, P for gaseous reactants/products, and knowing not to include pure solids and liquids in the calculation).

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 11:20 am
by Rodrigo2J
Mostly, the purpose is to help us understand that in phases like solids and liquids we wouldn't use them to calculate K or Q.

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Fri Jan 10, 2020 4:13 pm
by Angela Prince 1J
Amy Xiao 1I wrote:
DanielTalebzadehShoushtari2A wrote:It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species.


Thank you for pointing that out! We would have to convert everything into concentrations, not partial pressure, if there are aqueous solutions present.


Do you have to use partial pressure to find the equilibrium constant of a homogeneous gas equilibrium reactions or can we use concentration as well?

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Sat Jan 11, 2020 6:50 pm
by Chem_Mod
When dealing with a homogeneous gas equilibrium solving for K means solving in terms of partial pressure, if you were dealing with a homogeneous gas equilibrium and you used concentrations to find the equilibrium constant you would be obtaining Kc.

Kc and Kp are not always equal, you can read more about this in your book in topic 5H.3 (page 411-413)

Re: What is the Importance of homogeneous vs heterogeneous equilibria

Posted: Wed Jan 15, 2020 4:32 pm
by Amy Xiao 1I
Angela Prince 1J wrote:
Amy Xiao 1I wrote:
DanielTalebzadehShoushtari2A wrote:It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species.


Thank you for pointing that out! We would have to convert everything into concentrations, not partial pressure, if there are aqueous solutions present.


Do you have to use partial pressure to find the equilibrium constant of a homogeneous gas equilibrium reactions or can we use concentration as well?


I think that since you can use both ways, it will be based on what you are given in the problem and what is more convenient.