K Favors Products or Reactants
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K Favors Products or Reactants
How can we tell if the products or reactants are favored using K? I know a large K value shows that the products are favored, but what qualifies as large or small K values?
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Re: K Favors Products or Reactants
If K is greater than 1, then products are favored, and if K is less than 1, reactants are favored. This is because K=[products]/[reactants], so a value greater than one means the concentration of products is greater than that of reactants. So I guess you could say that a "large" K value is just greater than 1, and a "small" one is less than 1.
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Re: K Favors Products or Reactants
Large K values are anything above 10^3 and small K values are anything below 10^-3
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Re: K Favors Products or Reactants
Typically, what counts as a large k value is >10^3 and what counts as a small k value is <10^-3. However, essentially I use 1 as a sort of threshold for k. Whenever k is lower than 1, the reactants are favored. Whenever k is higher than 1, the products are favored. I hope this helps!
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Re: K Favors Products or Reactants
Rich Luong 1D wrote:Typically, what counts as a large k value is >10^3 and what counts as a small k value is <10^-3. However, essentially I use 1 as a sort of threshold for k. Whenever k is lower than 1, the reactants are favored. Whenever k is higher than 1, the products are favored. I hope this helps!
This is really helpful! I think 10^3 and 10^-3 are commonly used to reference when determining if K is large or small (if P or R is strongly favored). Since K is still a ratio, K = 1 would mean that the concentrations of reactants and products are equal and the forward/reverse rates are the same.
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Re: K Favors Products or Reactants
Gabby Magat 3F wrote:Rich Luong 1D wrote:Typically, what counts as a large k value is >10^3 and what counts as a small k value is <10^-3. However, essentially I use 1 as a sort of threshold for k. Whenever k is lower than 1, the reactants are favored. Whenever k is higher than 1, the products are favored. I hope this helps!
This is really helpful! I think 10^3 and 10^-3 are commonly used to reference when determining if K is large or small (if P or R is strongly favored). Since K is still a ratio, K = 1 would mean that the concentrations of reactants and products are equal and the forward/reverse rates are the same.
Thank you all for explaining! So if K=1, does that mean that the reaction is in equilibrium and the concentrations of the products and reactants are not changing? So K being less than one or greater than one means one side is favored, but K being equal to one means neither side is favored?
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Re: K Favors Products or Reactants
During lecture, I think that Dr. Lavelle said that for this course any K value that is less than 10^-3 will be considered small while any K value that is greater than 10^3 will be considered large. These values are meant to show whether one side is actually significantly more favored than the other.
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Re: K Favors Products or Reactants
The large k value is usually for 10^3 while small k value is 10^-3!
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Re: K Favors Products or Reactants
Amanda Bueno-Kling 2L wrote:Gabby Magat 3F wrote:Rich Luong 1D wrote:Typically, what counts as a large k value is >10^3 and what counts as a small k value is <10^-3. However, essentially I use 1 as a sort of threshold for k. Whenever k is lower than 1, the reactants are favored. Whenever k is higher than 1, the products are favored. I hope this helps!
This is really helpful! I think 10^3 and 10^-3 are commonly used to reference when determining if K is large or small (if P or R is strongly favored). Since K is still a ratio, K = 1 would mean that the concentrations of reactants and products are equal and the forward/reverse rates are the same.
Thank you all for explaining! So if K=1, does that mean that the reaction is in equilibrium and the concentrations of the products and reactants are not changing? So K being less than one or greater than one means one side is favored, but K being equal to one means neither side is favored?
Though K can be 1 at equilibrium, K not being 1 does not necessarily mean that the reaction is not at equilibrium and that concentrations are unchanging. A K of any value describes the equilibrium state, and concentrations can still be unchanging even if K=!1. But you're totally right that if K is equal to 1 then neither products nor reactants are favored at equilibrium—their concentrations (products as a whole and reactants as a whole, not necessarily individual reactants or products) are equal.
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Re: K Favors Products or Reactants
A large K would constitute as anything above 10^3 and a small K would be anything lower than 10^3.
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Re: K Favors Products or Reactants
If K > 10^3, equilibrium strongly favors P and if K<10^-3, equilibrium strongly favors R. Intermediate values (10^-3<K< 10^3) of K don't strongly favor either products or reactants but do slightly favor them.
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Re: K Favors Products or Reactants
A large k value is anything over 10^3 and a small value would be anything lower than 10^-3!
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Re: K Favors Products or Reactants
If the K value is small (K<10^-3) then the equilibrium sits to the left and if the K is large (K>10^3) then the equilibrium sits to the right.
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Re: K Favors Products or Reactants
A large K value is anything over 10^3 while a small K value is less than 10^-3, but if a K value is larger than 1, the products are favored, and if the K value is less than 1, the reactants are favored.
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Re: K Favors Products or Reactants
I just wanted to add that when K is any value in between the chemistry-defined cutoffs of 103 or 10-3, neither the reactants nor the products are favored. So we do not have a strong statement on whether the equilibrium favors the right or the left.
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Re: K Favors Products or Reactants
K>1 = products favored, since K=[products]/[reactants]. By the same logic, K<1 = reactants favored
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Re: K Favors Products or Reactants
In this case, large would be >1 and small would be <1. At 1, neither would be favored.
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Re: K Favors Products or Reactants
Using the equation Kc = [P]/[R], we can determine whether the products or reactants are favored. If the numerator (concentration of products) is greater than the denominator (concentration of reactants), the value of K will be greater than 1. If it were the other way around and the denominator were greater, that would mean the concentration of reactants is greater and K would be less than 1.
Re: K Favors Products or Reactants
It's important to use the rules that K<10^-3 is a small K and K>10^3 is a large K value because these are the values where either products or reactants are STRONGLY FAVORED, whereas the intermediate values between 10^-3 and 10^3 (besides K=1) are values where neither products nor reactants are strongly favored.
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