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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.
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.
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.
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.
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.
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.
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