K vs Q

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Erik Buetow 1F
Posts: 96
Joined: Fri Aug 30, 2019 12:15 am

K vs Q

Postby Erik Buetow 1F » Sun Jan 19, 2020 8:16 pm

When is it appropriate to use K and when should we use Q when doing an equilibrium problem?

Shimei_2F
Posts: 100
Joined: Fri Aug 09, 2019 12:17 am

Re: K vs Q

Postby Shimei_2F » Sun Jan 19, 2020 8:19 pm

K is used when a reaction is at equilibrium. Q can be used at any arbitrary stage of a reaction.

TarynD_1I
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

Re: K vs Q

Postby TarynD_1I » Sun Jan 19, 2020 8:21 pm

K is the equilibrium constant of an reaction that is already at equilibrium, while Q (reaction quotient) is used when the reaction is not already at equilibrium. Q is also used to show in which direction the reaction shifts (for example, when K>Q, then the reaction shifts to the right).

Janet Nguy 2C
Posts: 115
Joined: Sat Aug 24, 2019 12:17 am

Re: K vs Q

Postby Janet Nguy 2C » Sun Jan 19, 2020 9:02 pm

Q is calculated the same way as K, but Q is used to calculate the compositions for reactants and products at ANY TIME during the reaction, not just at equilibrium. You can compare Q to K to see if the reaction is at equilibrium, shifted to the left, or shifted to the right.

Kevin Antony 2B
Posts: 99
Joined: Sat Sep 07, 2019 12:16 am

Re: K vs Q

Postby Kevin Antony 2B » Sun Jan 19, 2020 9:08 pm

K is the reaction constant and remains the same at every point during the reaction, while Q is the ratio of products to reactants at a given point and can tell us which direction the reaction will proceed in next.

Trent Yamamoto 2J
Posts: 111
Joined: Sat Aug 17, 2019 12:18 am

Re: K vs Q

Postby Trent Yamamoto 2J » Sun Jan 19, 2020 9:24 pm

Usually the question will ask you to find the reaction quotient Q, which you will then compare to the given K to see if the reaction is already at equilibrium or if the reactants/products are favored.

Anna Chen 1K
Posts: 104
Joined: Thu Jul 25, 2019 12:18 am

Re: K vs Q

Postby Anna Chen 1K » Sun Jan 19, 2020 9:51 pm

K is used when a reaction is at equilibrium while Q is used when a reaction is at any point.

Louise Lin 2B
Posts: 97
Joined: Sat Aug 17, 2019 12:15 am

Re: K vs Q

Postby Louise Lin 2B » Sun Jan 19, 2020 9:52 pm

K is appropriate to use when the reaction is already at equilibrium. There is only one K value for each reaction and its circumstances (temperature, pressure, etc.) Q is appropriate to use at any point in time of the reaction, and is used to compare to K.

Alfred Barrion 2H
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Joined: Sat Jul 20, 2019 12:16 am

Re: K vs Q

Postby Alfred Barrion 2H » Sun Jan 19, 2020 9:54 pm

k is used when at equilibrium and q is used when not in equilibrium

Jesalynne 2F
Posts: 100
Joined: Wed Sep 18, 2019 12:18 am

Re: K vs Q

Postby Jesalynne 2F » Sun Jan 19, 2020 10:10 pm

K is used when the reaction is at equilibrium and Q can be used for other random times in the reaction. Q can be compared to K to see which direction the reaction will go.

Jesse Anderson-Ramirez 3I
Posts: 54
Joined: Thu Sep 26, 2019 12:18 am

Re: K vs Q

Postby Jesse Anderson-Ramirez 3I » Sun Jan 19, 2020 10:16 pm

K is a constant and is used when a reaction is in equilibrium. Q can be found at any point during a reaction and can be compared to K in order to find the direction of the reaction.

Nuoya Jiang
Posts: 99
Joined: Sat Sep 14, 2019 12:17 am

Re: K vs Q

Postby Nuoya Jiang » Sun Jan 19, 2020 10:17 pm

k is a constant and is used as a standard that we can compare with. Q is what we can calculate based on the data we've got.

Anushka Chauhan2B
Posts: 51
Joined: Sat Aug 24, 2019 12:16 am

Re: K vs Q

Postby Anushka Chauhan2B » Sun Jan 19, 2020 10:26 pm

K is calculated when the reaction is at equilibrium. Q is when the reaction is not at equilibrium.

205154661_Dis2J
Posts: 109
Joined: Wed Sep 18, 2019 12:21 am

Re: K vs Q

Postby 205154661_Dis2J » Sun Jan 19, 2020 11:35 pm

K is a constant used when the rxn is at equilibrium. Q can be used at any time in the rxn to determine the shift of a rxn, either left or right.

Kennedi2J
Posts: 101
Joined: Wed Sep 18, 2019 12:20 am

Re: K vs Q

Postby Kennedi2J » Sun Jan 19, 2020 11:39 pm

You can think of Q on a "number line" with K where Q is on either side of K and K is in the middle like 0. When a reaction is not at equilibrium you want to find Q to determine which way the rxn will shift to reach K at equilibrium. If Q is less than K the rxn will move right towards K, the equilibrium, in the middle of the "number line".


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