K vs. Q

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Lilly Catarozoli 1B
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K vs. Q

Postby Lilly Catarozoli 1B » Thu Jan 07, 2021 6:11 pm

Hi! Just to clarify, Q and K are both the ratio of products over reactants, the only difference is that Q is used when the reaction is not at equilibrium? Thanks!

SalmaQ
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Re: K vs. Q

Postby SalmaQ » Thu Jan 07, 2021 6:13 pm

Hello Lilly!
The time when we would use the reaction quotient (Q) would be any time during the reaction and like you stated, the K constant is used for when at an equilibrium! Hope this helps!

Karl Yost 1L
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Re: K vs. Q

Postby Karl Yost 1L » Thu Jan 07, 2021 6:13 pm

Exactly! Q is just [P]/[R] at any given time. When Q = K, then we say the reaction is at equilibrium.

SalmaQ
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Re: K vs. Q

Postby SalmaQ » Thu Jan 07, 2021 6:14 pm

And yes to clarity both have the same ratio [Products]/[Reactants].

Sabrina Galvan 3J
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Re: K vs. Q

Postby Sabrina Galvan 3J » Thu Jan 07, 2021 6:15 pm

Yup! They are both calculated the same way, and Q is used as a way to compare the state of the system and whether what direction the reaction is going relative to the value of K.

Jiapeng Han 1C
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Re: K vs. Q

Postby Jiapeng Han 1C » Thu Jan 07, 2021 7:56 pm

Q could be used at anytime of a reaction that is happening, it is just the ratio of products to reactants. However, K shall only be used when the reaction reaches equilibrium.

Akriti Ratti 1H
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Re: K vs. Q

Postby Akriti Ratti 1H » Thu Jan 07, 2021 7:57 pm

Hi! What you wrote is correct. We call Q the reaction quotient.

Rajshree 1F
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Re: K vs. Q

Postby Rajshree 1F » Sat Jan 09, 2021 10:21 am

yes, Q is the ratio of [P]/[R] when the system is not at equilibrium (K)

Krish_Ajmani_3J
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Re: K vs. Q

Postby Krish_Ajmani_3J » Sat Jan 09, 2021 12:32 pm

You are exactly right. Q=[P]/[R] but can be used even if the system is not in equilibrium.
Some important things to keep in mind regarding Q and K:
Q=K at equilibrium.
If Q<K, the reaction will go forward/towards products.
If Q>K, the reaction will go backward/towards reactants.

Simi Kapila_3E
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Re: K vs. Q

Postby Simi Kapila_3E » Sat Jan 09, 2021 1:04 pm

Yes, Q is used anytime the reaction is not in equilibrium and K is only used when the reaction is in equilibrium. You can use the Q value to comparatively to the K value, to see where you are in the reaction (to see if it needs to shift right or left).

Sophia Spungin 2E
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Re: K vs. Q

Postby Sophia Spungin 2E » Sat Jan 09, 2021 1:15 pm

They are calculated the same way, however when calculating K the concentrations of product and reactants must be those at which the reaction is at equilibrium, whereas the concentrations of products and reactants used to calculate Q can be from any given point at which the reaction is occurring.

Melis Kasaba 2B
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Re: K vs. Q

Postby Melis Kasaba 2B » Sat Jan 09, 2021 1:16 pm

Yes, that is correct. Q is the reaction quotient and K is the equilibrium constant. We use Q to figure out which direction a reaction will shift to reach equilibrium. If K > Q, the forward reaction is favored, converting reactants into products. If K < Q, the reverse reaction is favored, converting products into reactants. If K = Q, we know the system is at equilibrium and neither the forward nor reverse reaction is favored; instead they proceed at equal rates.

Liam Bertrand 3
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Re: K vs. Q

Postby Liam Bertrand 3 » Sat Jan 09, 2021 1:17 pm

Yes, Q just applies to a reaction that is not at equilibrium, while K is at equilibrium. You can compare the two values to determine which direction the reaction is going.

Inderpal Singh 2L
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Re: K vs. Q

Postby Inderpal Singh 2L » Sat Jan 09, 2021 1:33 pm

Yes! Q is when the reaction is not at equilibrium.

Sean Wang 1F
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Re: K vs. Q

Postby Sean Wang 1F » Sat Jan 09, 2021 3:04 pm

Yes, Q is the reaction quotinent. Use Q when the reaction is not at equilibrium and use K when the reaction is at equilibrium.

Jason Knight - 1F
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Re: K vs. Q

Postby Jason Knight - 1F » Sat Jan 09, 2021 3:29 pm

Q is the reaction quotient of the reaction and can be used to analyze the state of the system. It is important to note both Q and K are calculated with the same formula, but when calculating Q we do not know the state of the system necessarily. If Q>K then the reverse reaction is favored, and if Q<K then the forward reaction is favored. If Q=K, which is rare, then we can say the reaction is at equilibrium.

Ava Nickman
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Re: K vs. Q

Postby Ava Nickman » Sat Jan 09, 2021 3:47 pm

yup! that's correct

Carly_Lipschitz_3H
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Re: K vs. Q

Postby Carly_Lipschitz_3H » Sat Jan 09, 2021 4:43 pm

K is used only when the reaction is at equilibrium. Q is used when we are unsure whether or not the reaction is at equilibrium. Although Q can be equal to K (meaning the reaction at that point is at equilibrium), Q can also be greater than or equal to K. K is a constant, whereas Q is not.

Rylee Mangan 1K
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Re: K vs. Q

Postby Rylee Mangan 1K » Sat Jan 09, 2021 5:28 pm

We would use Q when the reaction has been disrupted/ no longer in equilibrium right?

keely_bales_1f
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Re: K vs. Q

Postby keely_bales_1f » Sat Jan 09, 2021 5:43 pm

So if we are given Kc and then are told to calculate Q with the given concentrations of the products and reactants, Q would tell us if the reaction is at equilibrium or if the reaction leans toward the products/reactants?

Amanda Chang 2B
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Re: K vs. Q

Postby Amanda Chang 2B » Sat Jan 09, 2021 6:18 pm

keely_bales_1f wrote:So if we are given Kc and then are told to calculate Q with the given concentrations of the products and reactants, Q would tell us if the reaction is at equilibrium or if the reaction leans toward the products/reactants?


Yup, that's right!

dana hu 1B
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Re: K vs. Q

Postby dana hu 1B » Sat Jan 09, 2021 6:25 pm

Q is a quantity that changes as a reaction system approaches equilibrium. (have not yet reached equilibrium; reaction in progress)
K is the numerical value of Q at the "end" of the reaction when equilibrium is reached.

Logan Wiedemann 3J
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Re: K vs. Q

Postby Logan Wiedemann 3J » Sat Jan 09, 2021 6:30 pm

Yep, you've got it! Q is just when the reaction isn't at equilibrium!

Bryan Le 2K
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Re: K vs. Q

Postby Bryan Le 2K » Sat Jan 09, 2021 7:12 pm

Yes! Q is used when the system hasn't reach equilibrium yet while K is used when the system has reach equilibrium.

Tatyana Bonnet 2H
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Re: K vs. Q

Postby Tatyana Bonnet 2H » Sat Jan 09, 2021 8:18 pm

Yes Q is used at any time to see where the reaction is at in relation to equilibrium and K is the constant value at equilibrium. If Q=K then it is at equilibrium.

Brenda Silva 1B
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Re: K vs. Q

Postby Brenda Silva 1B » Sat Jan 09, 2021 9:35 pm

Yes, Q and K are both the ratio of [products]/ [reactants] and the only difference is that K is used when equilibrium has been reached and Q is used anytime the reaction is occurring.

Margaret Xu 3C
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Re: K vs. Q

Postby Margaret Xu 3C » Sun Jan 10, 2021 3:46 am

Hi Lilly! You are correct. The reaction quotient, Q, is used to represent the concentration/partial pressure of products divided by the concentration/partial pressure of reactants of the reaction at ANY time. The equilibrium constant, K, represents the reaction at equilibrium.

Kyle Dizon 3A
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Re: K vs. Q

Postby Kyle Dizon 3A » Sun Jan 10, 2021 9:32 am

Correct. Product divided by reactants will determine the K. If reaction is not at equilibrium, Q can be determined in order to identify if the reactant or products will be favored.

Shalyn Kelly 3H
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Re: K vs. Q

Postby Shalyn Kelly 3H » Sun Jan 10, 2021 9:36 am

Hi! You're correct! K is when the system is at equilibrium and Q is when the system is not, so if Q=K then the system has reached equilibrium.

Joel Meza 3I
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Re: K vs. Q

Postby Joel Meza 3I » Sun Jan 10, 2021 11:53 am

Yes, that's correct, Q is just the ratio at any time during the reaction and K (equilibrium constant) is the ratio when the reaction is at equilibrium.

Kat Stahl 2K
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Re: K vs. Q

Postby Kat Stahl 2K » Sun Jan 10, 2021 12:25 pm

Yep you're right Q is when the reaction is not at equilibrium and K is when it is at equilibrium, but it is the same calculation.

Emma Strassner 1J
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Re: K vs. Q

Postby Emma Strassner 1J » Sun Jan 10, 2021 2:42 pm

Yes, Q and K are both the same process of using the ratio of products to reactants. The only difference is that Q is when the reaction is not at equilibrium.

Daniela Santana 2L
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Re: K vs. Q

Postby Daniela Santana 2L » Sun Jan 10, 2021 3:28 pm

Yes you are correct. Q is used when they are not equilibrium values yet. You can find Q at any time during the reaction but K is only when the reaction is at equilibrium.

Isabella Cortes 2H
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Re: K vs. Q

Postby Isabella Cortes 2H » Sun Jan 10, 2021 3:35 pm

Yes, you are correct! Q is found the same way as K and you use Q when the reaction has not reached equilibrium.

Madilyn Schindler 3E
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Re: K vs. Q

Postby Madilyn Schindler 3E » Sun Jan 10, 2021 3:49 pm

Yes, both Q and K are calculated using the same method. The only difference is that K is the ratio of concentrations when the system is at equilibrium. Q is the ratio of concentrations when the system isn't at equilibrium.

jia207
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Re: K vs. Q

Postby jia207 » Sun Jan 10, 2021 4:27 pm

K is used when a reaction is at equilibrium and Q is used when an equation is not over equilibrium. They are both always Products/Reactants

Claudia_Danysh_2B
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Re: K vs. Q

Postby Claudia_Danysh_2B » Sun Jan 10, 2021 4:45 pm

Yes! Just to clarify even more, Q is the reaction quotient while K is the equilibrium constant!

Sofia Lombardo 2C
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Re: K vs. Q

Postby Sofia Lombardo 2C » Sun Jan 10, 2021 7:07 pm

Q and K are both calculated using the [p]/[r]. Q is the reaction quotient, and is used at any time where the reaction is not at equilibrium. K is for when the reaction is at equilibrium.

Zainab Jamali 1H
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Re: K vs. Q

Postby Zainab Jamali 1H » Sun Jan 10, 2021 7:18 pm

You're correct! I believe Q can be calculated at any time during the reaction (including at equilibrium) but if it is specified that the reaction is at equilibrium you can use K instead.

Karen Zheng_2K
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Re: K vs. Q

Postby Karen Zheng_2K » Sun Jan 10, 2021 7:19 pm

K is only used when a system is in equilibrium (K=Q)!

Aria Movassaghi 1A
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Re: K vs. Q

Postby Aria Movassaghi 1A » Sun Jan 10, 2021 9:50 pm

Yes, it is the same equation but k is at equilibrium.

Mansi Solanki 3A
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Re: K vs. Q

Postby Mansi Solanki 3A » Sun Jan 10, 2021 10:07 pm

You're right! The K is used for the system when it is in equilibrium while Q can be used at any point in time for the system.

Gian Boco 2G
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Re: K vs. Q

Postby Gian Boco 2G » Sun Jan 10, 2021 10:27 pm

Yep, Q is just the expression anytime during the expression wheres as K is the value for when it is in equilibrium.

LeahSWM 2E
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Re: K vs. Q

Postby LeahSWM 2E » Sun Jan 10, 2021 10:46 pm

Yes, K is used when the equation is at equilibrium while Q is when it is not.

Mina Tadros 3L
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Re: K vs. Q

Postby Mina Tadros 3L » Sun Jan 10, 2021 10:50 pm

Correct. Whenever you take the ratio of the concentration (or partial pressure) of products over reactants when it is not at equilibrium, you are solving for Q, the reaction quotient. If the reaction is at equilibrium, then the ratio of products to reactants is the equilibrium constant, K.

Brandon McClelland3L
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Re: K vs. Q

Postby Brandon McClelland3L » Sun Jan 10, 2021 11:11 pm

Q represents products/reactants in general, while K only represents products/reactants at equilibrium.

Daniel Hernandez 1G
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Re: K vs. Q

Postby Daniel Hernandez 1G » Sun Jan 10, 2021 11:13 pm

They are both calculated the same way however Q reflects the state of the reaction whereas K represents the reaction at equilibrium.

TiffanyBrownfield 2I
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Re: K vs. Q

Postby TiffanyBrownfield 2I » Sun Jan 10, 2021 11:23 pm

Yes Q and K are essentially the same thing. The only difference is that K is the concentration of products and reactants when it is at equilibrium and Q is at any time during the reaction. Q's value relative to K can be used to determine the direction that the reaction is tending towards.

Rayna Irving 2C
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Re: K vs. Q

Postby Rayna Irving 2C » Sun Jan 10, 2021 11:26 pm

Q and K are found the exact same way with the ratio of products/reactants, but K is just specifically referring to the value when the reaction reaches equilibrium.

Devan Nathu - 2H
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Re: K vs. Q

Postby Devan Nathu - 2H » Sun Jan 10, 2021 11:28 pm

Just to clarify, will we always be able to assume that the reaction is at equilibrium when K=Q? Thanks!!

Mehreen 3I
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Re: K vs. Q

Postby Mehreen 3I » Sun Jan 10, 2021 11:30 pm

Lilly Catarozoli 1B wrote:Hi! Just to clarify, Q and K are both the ratio of products over reactants, the only difference is that Q is used when the reaction is not at equilibrium? Thanks!

Yes, exactly! The Q is known as the reaction quotient and it is used when the reaction is not at equilibrium (all other times).

Caelin Brenninkmeijer 1G
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Re: K vs. Q

Postby Caelin Brenninkmeijer 1G » Sun Jan 10, 2021 11:31 pm

They are both calculated using the same method ([P]/[R]), but Q represents the reaction at any time while K represents the reaction at equilibrium.

Gwen Casillan 3E
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Re: K vs. Q

Postby Gwen Casillan 3E » Sun Jan 10, 2021 11:35 pm

Devan Nathu - 2H wrote:Just to clarify, will we always be able to assume that the reaction is at equilibrium when K=Q? Thanks!!


Yes, since K is the equilibrium constant, when Q (the reaction quotient) is equal to K, the reaction is at equilibrium.

sabrina ghalambor 2J
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Re: K vs. Q

Postby sabrina ghalambor 2J » Sun Jan 10, 2021 11:35 pm

Q is P/R at any time during the reaction and we can use it to determine which reaction is favored.


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