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### K vs Q

Posted: Sat Jan 11, 2020 2:54 pm
I have a question about when to use K and Q. Also, what's the main difference between the two. Thank you. :)

### Re: K vs Q

Posted: Sat Jan 11, 2020 3:04 pm
The primary difference between K and Q is that K describes a reaction at equilibrium, whereas Q describes a reaction that is not at equilibrium.

### Re: K vs Q  [ENDORSED]

Posted: Sat Jan 11, 2020 3:06 pm
Donavin Collins 1F wrote:I have a question about when to use K and Q. Also, what's the main difference between the two. Thank you. :)

Hi Donavin,

From what I understand, K is the equilibrium constant while Q is the reaction quotient. K is calculated using the concentrations of reactants and products at equilibrium. Q is not necessarily at equilibrium. Equilibrium is achieved when K=Q. For a more in-depth explanation and helpful example, I recommend viewing this video: https://www.youtube.com/watch?v=gY_lyPO_DI0. I hope this helps!

-Rebecca

### Re: K vs Q

Posted: Sat Jan 11, 2020 3:11 pm
^^^what they said is true, but ALSO Q is useful to use when you are trying to see where the reaction is in comparison to equilibrium, so like when Q is less than K then you know that more products need to be formed to reach equilibrium, when Q > K you know that more reactants need to be formed to reach equilibrium, and when Q=K you know that the reaction is at equilibrium

### Re: K vs Q

Posted: Sat Jan 11, 2020 3:14 pm
K is the equilibrium constant, while Q is the reaction quotient. Though they are calculated the same way, Q can be calculated at any time during the reaction, while K represents when the reaction is at equilibrium. If Q<K, then [reactants] > [products] and the forward reaction is favored. The opposite goes if Q>K. If Q=K, the reaction is at equilibrium at that point in the reaction.

### Re: K vs Q

Posted: Sat Jan 11, 2020 3:29 pm
The difference between K and Q is K is the concentration at equilibrium and Q is the reaction quotient which is calculated the same as K and can be calculated at any time during the reaction.

### Re: K vs Q

Posted: Sat Jan 11, 2020 3:35 pm
K is the equilibrium constant (this tells us where the equilbrium sits), while Q is the reaction quotient (this determines which direction a rxn will proceed)

### Re: K vs Q

Posted: Sat Jan 11, 2020 9:44 pm
Donavin Collins 1F wrote:I have a question about when to use K and Q. Also, what's the main difference between the two. Thank you. :)

k is the equilibrium constant that is temperature dependent (the same number for every temperature); it does not change unless temperature changes (as long as the reaction is at equilibrium). Q is just like k, however, it is when the reaction as not yet reached equilibrium.