Q compared to K

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Mary Grace Stevens 3G
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Q compared to K

Postby Mary Grace Stevens 3G » Wed Jan 06, 2021 4:22 pm

If we are comparing Q to K in a reaction that isn't in equilibrium yet, with the reactants being larger than the products, thus leading to a smaller Q, does that also equate to a larger K? If so, is the relationship between Q and K inversely proportional, or a reciprocal? Thanks.

Stuti Pradhan 2J
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Re: Q compared to K

Postby Stuti Pradhan 2J » Wed Jan 06, 2021 4:28 pm

You are correct in that Q would be less than K, but K would not change. The equilibrium constant, K, only changes for a reaction due to a change in temperature. Therefore, not having reached equilibrium does not change the equilibrium constant. Calculating Q in this situation would let us know that in relation to K, the established equilibrium constant, Q is smaller. Q and K are not proportional or inversely proportional in any way. The only thing to know is that when Q<K, that means more products need to form for the reaction to reach equilibrium, and when Q>K, more reactants need to form for the reaction to reach equilibrium.

Hope this helps!

Josh Chou 3K
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Re: Q compared to K

Postby Josh Chou 3K » Wed Jan 06, 2021 4:31 pm

I don't think K should be changing at all because it is the equilibrium constant. The reaction should tend towards that constant, and Q just gives us a number to compare to K at any time during the reaction. Q and K are not inversely proportional because K should not change despite the Q value changing

Kiyoka Kim 3C
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Re: Q compared to K

Postby Kiyoka Kim 3C » Wed Jan 06, 2021 4:53 pm

I believe as long as you are looking at the same reaction with the same conditions, K does not change. So when comparing Q to K there are only three possibilities: Q equals K, is larger than K, or smaller than K.

Lauren To 1E
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Re: Q compared to K

Postby Lauren To 1E » Wed Jan 06, 2021 4:57 pm

I don't think Q and K have an inverse or reciprocal relationship because K is not dependent upon the value of Q. K is a value of the product to reactant ratio at equilibrium that stays constant at that temperature, and is not affected by Q. Q changes because as the reaction gets closer to reaching equilibrium Q will slowly become closer to K until the system reaches equilibrium, at which point Q will be the same as K. When Q>K it means that more reactant needs to be formed in order to reach the equilibrium ratio and when Q<K it means that more product needs to be formed in order to reach the equilibrium ratio. I hope that made sense!

VincentLe_3A
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Re: Q compared to K

Postby VincentLe_3A » Wed Jan 06, 2021 5:16 pm

The equilibrium constant K does not change as long as the temperature is held constant. We compare Q, the reaction quotient which is a certain ratio at a certain time, to the K, which is the ratio at the reaction equilibrium. When Q<K, this indicates more reactants than products compared to the equilibrium ratio so the reaction will go in the forward direction and favor the creation of products to reach equilibrium. However, when Q>K, this indicates there are more products than reactants compared to the equilibrium ratio so the reaction will go in the reverse direction and favor the creation of the reactants to reach equilibrium.

aashmi_agrawal_3d
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Re: Q compared to K

Postby aashmi_agrawal_3d » Wed Jan 06, 2021 7:06 pm

K does not change because it is a constant. If Q is greater than K, then you know more reactants will form to reach equilibrium and if Q is less than K, then you know that more products must be formed.


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