K vs. Q

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Katie Bart 1I
Posts: 94
Joined: Sat Aug 24, 2019 12:16 am

K vs. Q

Postby Katie Bart 1I » Wed Jan 08, 2020 11:49 pm

What is the difference between K and Q? Since the same process is used to find both values, how can they be equal to different numbers?

Jasmine W 1K
Posts: 13
Joined: Sat Sep 07, 2019 12:18 am

Re: K vs. Q

Postby Jasmine W 1K » Thu Jan 09, 2020 12:19 am

K is the equilibrium constant, while Q is the reaction quotient and can, therefore, be used at any time during the reaction. This means that Q can be calculated even when the reaction is not at equilibrium, leading to K and Q possibly being different numbers. by comparing the different values of K and Q, you can find the direction that the reaction is favoring at the time. If Q < K, then [R] > [P], so the forward reaction is favored. If Q > K, then [P] > [R], so the reverse reaction is favored.

Christineg1G
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Joined: Fri Aug 09, 2019 12:15 am
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Re: K vs. Q

Postby Christineg1G » Thu Jan 09, 2020 9:00 am

K would be known as the equilibrium constant, Kc. K can also be used to calculate the partial pressure of a species at equilibrium, Kp. Q is the reaction quotient and it is used to determine which direction a reaction will proceed. Q or Qc or Qp are calculated the same way as K, but for Q, the reaction doesn't have to be in equilibrium.

Hui Qiao Wu 1I
Posts: 39
Joined: Fri Aug 30, 2019 12:16 am

Re: K vs. Q

Postby Hui Qiao Wu 1I » Sat Jan 11, 2020 10:46 am

Yup, like everybody else has said, K is for when you know that the reaction is in equilibrium and Q is when you are not sure if the reaction is in equilibrium.

Anika Chakrabarti 1A
Posts: 86
Joined: Sat Aug 24, 2019 12:17 am

Re: K vs. Q

Postby Anika Chakrabarti 1A » Sat Jan 11, 2020 10:51 am

K is a fixed ratio and will therefore always be the same number (for each reaction at a certain temperature), but Q is the P/R ratio calculated at any point in the reaction. Q can be used to figure out whether a reaction is at equilibrium, and if not, which direction the reaction is moving.

005333065
Posts: 6
Joined: Sat Sep 14, 2019 12:16 am

Re: K vs. Q

Postby 005333065 » Sat Jan 11, 2020 11:07 am

K and Q have the same values at equilibrium. That is why, if they are not equal you can see whether the reaction going forwards or backward by comparing the Q and the K. If Q is bigger than K, that means the reaction at this time has more products than it's equilibrium state, which is what the K value is. So we will see that this reaction will rely more on to the left side and produce more reactants to reach equilibrium.

san_2F
Posts: 99
Joined: Sat Jul 20, 2019 12:15 am

Re: K vs. Q

Postby san_2F » Sat Jan 11, 2020 1:26 pm

K is the fixed equilibrium constant value for a certain reaction. Q is the reaction quotient and is used when it is certain that the reaction is not at equilibrium yet. For example, if you add more products, the reaction will not be at equilibrium the moment you add more products, so you would calculate the Q, compare it to K and see how the reaction would respond to make itself reach equilibrium.

Zoe Gleason 4F
Posts: 41
Joined: Tue Jul 23, 2019 12:15 am

Re: K vs. Q

Postby Zoe Gleason 4F » Sat Jan 11, 2020 2:03 pm

The difference in K and Q is because K is taken when the reaction is at equilibrium and Q is taken at another point to determine if the reaction has reached equilibrium. The values of Q and K also help to determine which way the reaction will move from the point where Q was taken. This can also help with ICE tables to determine if the change will be positive or negative.

Madelyn Romberg 1H
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Joined: Tue Oct 02, 2018 12:16 am

Re: K vs. Q

Postby Madelyn Romberg 1H » Sat Jan 11, 2020 3:14 pm

K is an equilibrium constant that is most favorable to the reaction under certain conditions. Q measures where the reaction is at any given time in relationship to K.

Celine 1F
Posts: 103
Joined: Fri Aug 02, 2019 12:16 am

Re: K vs. Q

Postby Celine 1F » Sat Jan 11, 2020 3:25 pm

K is found when the reaction is at equilibrium, whereas Q can be found at any time during the reaction. Q helps us identify which way the reaction is proceeding

305385703
Posts: 90
Joined: Thu Jul 11, 2019 12:15 am

Re: K vs. Q

Postby 305385703 » Sat Jan 11, 2020 3:58 pm

K is the experimentally determined value of the ratio of products to reactants after the reaction has reached equilibrium. Q is the current ratio of products to reactants in a reaction.


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