K vs Q

[Erik Buetow 1F]

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

[Shimei_2F]

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

[TarynD_1I]

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]

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]

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]

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]

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

[Louise Lin 2B]

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]

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

[Jesalynne 2F]

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]

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]

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]

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

[205154661_Dis2J]

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]

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".