K and Q

[Shuyi Yu 1B]

If Q and K both have the same formula why are they not equal to each other?

[Ariel Cheng 2I]

They have the same formula but don't equal each other because K is calculated using molarities at equilibrium but Q is calculated using molarities at any point in time during the reaction. We can then use Q and compare it to K to see at where the reaction is at. If Q<K, then a forward reaction is favored because Q and K are products/reactants and we need more products to increase the value of Q. The opposite is true if Q>K.

[Karina Jiayu Xu 4E]

K is used for the exact equilibrium state and Q is used for anytime during the reaction. When they are not exactly the same then the current reaction is leaning one direction or the other.

[SydBenedict2H]

K calculates the equilibrium constant (either with partial pressure P or concentration n/v) whereas Q can be use anytime and is useful in its comparison to a K value. Whether it is greater than or less than the reactions K value, dictates which direction the reaction is going and if there are more products or reactants.

[Ethan Yi 1K]

K is the [products]/[reactants] at equilibrium. Q can be used anytime during the reaction. For instance, at the very start of the reaction, there may be a lot more reactants than products, and at this point, [products]/[reactants] would be Q, not K bc the reaction is not at equilibrium yet.

[Harshita Talkad 4L]

K is calculated with the concentrations of the reactants and products when the reaction is at equilibrium, which means K will always be constant as long as it is the same reaction at the same temperature. Q can be calculated at any point in the reaction, so there will be different concentrations of reactants and products at each point in time, so Q is different depending on when in the reaction it is calculated. Q is compared to K to determine if the reaction is at equilibrium at that point in time.

[Alyssa Wilson 2A]

I agree with the above statements, and Q is known as the reaction coefficient, which is similar to k, but it can be used in any stage of the reaction, where k is used and solids and liquids do not contribute into k. K is the equilibrium constant and the rate of the forward reaction will equal the rate of the reverse reaction.

[404982241]

K is the equilibrium constant. Its value is only true once the reaction has reached equilibrium. Q can be calculated any time during the reaction. Regardless of the amount of products and reactants used, K will always be the same.