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Do the terms homogeneous and heterogeneous equilibrium only apply to the phases of the reactants and products used in the equation for K or are other reactants and products (such as solids and liquids) in the overall reaction taken into consideration when determining if the reaction is homogeneous or heterogeneous?
I believe that you look at the overall reaction when determining whether it is a homogenous or heterogenous equilibrium. For example, if the reaction has a solid, even though you would not put the solid in the equation for K, it would make it a heterogenous equilibrium.
A system in homogeneous equilibrium exists when the reaction in question contains reactants and products that are all in the same phase (either in solution or gaseous). A system in heterogeneous equilibrium exists when the reaction contains reactants or products that are either in a solid or liquid phase. The molar concentration of solids and liquids don't change in reactions, and therefore they aren't included in the K expression. So the definitions of homogeneous and heterogeneous equilibriums don't rely on what is contained in the K expression as much as the K expression relies on the state of the reaction.
Agreeing with others, I believe you look at the overall reaction even if you are only calculating Kc or Kp. So, you look at each phase in the entire reaction and that’s what determines if the equilibrium is homogeneous or heterogeneous.
my understanding is that homogenous and heterogenous differ in the state of which the products and reactants are in. A certain reaction is heterogenous if there is more than one state of a substance in the reaction.
The overall reaction would be used in determining if a system has heterogeneous or homogeneous equilibrium. Despite solids and liquids not being included in the expression of the equilibrium constant, these phases are still present and do not change concentration or pressure in reactions. Because these phases still exist in this system, they are included in classifying equilibrium. In any circumstances, the presence of multiple phases of any kind in a system would result in heterogeneous equilibrium whereas the existence of a singular phase in an entire reaction can be classified as homogeneous equilibrium.
Yes you would look at the overall reaction! Even though solids and liquids are omitted from the K expression, they are still used to determine whether the reaction is homogenous or heterogenous.
To determine if the reaction is homogenous or heterogenous, you should look at all of the compounds present in the reaction including those that won't be included in the calculations for K or Q.
In addition, could someone give me an example of a heterogenous equilibrium? I am confused on how we could have one or more product/reactant in "different phases" or what that really means in the context of a reaction.
Izamary Marquez 2H wrote:In addition, could someone give me an example of a heterogenous equilibrium? I am confused on how we could have one or more product/reactant in "different phases" or what that really means in the context of a reaction.
A common reaction that is heterogenous is ice and water at equilibrium: H20(s) ⇌ H20(l). At 0 degrees C, ice is in thermal equilibrium with water.
Although we do not include solids and liquids in equilibrium constant equations, they do factor into whether or not a substance is heterogenous or homogenous. This is because while they do not affect the equilibrium constant, they still are apart of what makes up the substance.
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