q and K

[Funmi Baruwa]

Hey, just wanted to clarify that the only difference between Q and k is that K has to be measured at a certain temoerature?

[Funmi Baruwa]

Also what is the temperature K is measured at? Is it always 25 degrees C?

[Anna Li 3B]

The difference between Q and K is when they are measured. K is measured when the reaction is at equilibrium, and Q can be measured at any time during the reaction (including the time at which the reaction is at equilibrium, when Q = K).

K does not always have to be measured at 25 degrees C. It is common though, because that is typical room temperature. Because Q and K change as a function of temperature, it is important that they are measured at the same T for the same reaction in order to be compared.

[vanessanguyen3I]

Both are calculated the same way but Q is used when the reaction is not at equilibrium.

[Thomas Vu 1A]

Also Q's position relative to K indicates the direction the reaction will proceed in with Q<K indicating a forward shift for example

[Joshua Swift]

K is the equilibrium constant and can only be calculated at equilibrium.
Q is the reaction quotient and can be calculated the same way as K, but at any point in the reaction.
If T is not given, it is implied the reaction is at 25 degrees C.

[Sophia Spungin 2E]

I believe that the difference between Q and K is only that Q is measured before the reaction has had adequate time to reach equilibrium whereas K is measured once the reaction has reached equilibrium. I do not think that they are necessarily measured at different temperatures. A value of K for a reaction as well as a value of Q can be found at any temperature, however the value of K will differ when the reaction is at different temperatures.

[Gwirnowski 3B]

Q is the measure of the concentrations of a reaction headed towards equilibrium when it has not yet reached it yet. It tells us information of whether the reaction is favoring the forward or reverse reaction and, correct me if I am wrong, but can be measured at any time of the reaction as long as the temperature is the same as it will be when it reaches equilibrium, or else its implications will be skewed.

[Mackenzie Van Val 3E]

The difference between Q and K is that K is only measured at equilibrium, and, if the reaction quotient is calculated at any other point during the reaction, it is called Q. K can come at different temperatures, because equilibrium occurs at different temperatures, but K will vary from temperature to temperature.

[gabbi_r2C]

Hi there! So Q and K are different because K is the reaction constant at equilibrium, and Q is the ratio of products to reactants at any point during the reaction (not usually at equilibrium; if it is, then Q will be equal to K). K can be measured at any temperature, but will change as temperature changes; the problem will typically give you the temperature the equation is being measured at, and if not, then yeah usually at 25 degrees C.

[Aanya Tanti 3C]

K is when the reaction is at equilibrium and Q can be at any point (including equilibrium) and their equations are the same. Q and K are generally measured at 25 degrees celsius as this is room temperature, but they can be measured at any temperature. Both are affected by change in temperature, so to compare the two, ensure that the temperature is the same.

[Anusha Chaudhary 1J]

The key difference between Q and K is when the concentrations are calculated. K is found specifically when the reaction has reached equilibrium, whereas Q is found at any other time of the reaction. K and Q can be found at any temperature, however, K will differ when the reaction is at different temperatures.