High School Kinetics and Equilibrium
IN THIS LESSON
Learn more about the reaction quotient Q.
1/4/25: I consider this lesson complete right now, but I am willing to edit it as needed.
The reaction quotient (Q) of a reaction is essentially the same as the K. The main difference is the case in which each is used: calculate K when you are sure the system is at equilibrium. Q can be calculated when you are unsure if it’s at equilibrium, and comparing it to the K can help find if the system is or is not at equilibrium. If Q and K are not equal, the Q can help indicate which way the system needs to shift to come back to equilibrium.
Q is calculated using the same equation as K:
If Q < K, the system needs to shift right, or towards the products to reach equilibrium. If Q > K, then the system needs to shift left, or towards the reactants to reach equlibrium.